diff --git a/L2J_Mobius_1.0_Ertheia/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_1.0_Ertheia/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index 00ce2e0eac..a155c6bffc 100644
--- a/L2J_Mobius_1.0_Ertheia/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_1.0_Ertheia/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7370,23 +7370,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7539,8 +7536,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7563,20 +7558,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7599,8 +7580,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_2.5_Underground/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_2.5_Underground/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index 1d6f507e2e..90cdbb091b 100644
--- a/L2J_Mobius_2.5_Underground/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_2.5_Underground/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7377,23 +7377,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7546,8 +7543,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7570,20 +7565,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7606,8 +7587,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_3.0_Helios/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_3.0_Helios/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index 594e5da12e..8a121eafe8 100644
--- a/L2J_Mobius_3.0_Helios/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_3.0_Helios/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7379,23 +7379,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7548,8 +7545,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7572,20 +7567,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7608,8 +7589,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_4.0_GrandCrusade/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_4.0_GrandCrusade/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index e6adc8202a..62ea0cf7dd 100644
--- a/L2J_Mobius_4.0_GrandCrusade/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_4.0_GrandCrusade/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7374,23 +7374,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7543,8 +7540,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7567,20 +7562,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7603,8 +7584,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_5.0_Salvation/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_5.0_Salvation/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index d5c3f13c6f..5389548045 100644
--- a/L2J_Mobius_5.0_Salvation/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_5.0_Salvation/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7356,23 +7356,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7525,8 +7522,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7549,20 +7544,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7585,8 +7566,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_5.5_EtinasFate/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_5.5_EtinasFate/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index b78eb15f42..70af78d96d 100644
--- a/L2J_Mobius_5.5_EtinasFate/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_5.5_EtinasFate/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7356,23 +7356,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7525,8 +7522,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7549,20 +7544,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7585,8 +7566,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_6.0_Fafurion/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_6.0_Fafurion/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index 8226509789..6de15a37d3 100644
--- a/L2J_Mobius_6.0_Fafurion/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_6.0_Fafurion/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7357,23 +7357,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7526,8 +7523,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7550,20 +7545,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7586,8 +7567,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_7.0_PreludeOfWar/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_7.0_PreludeOfWar/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index e263e2a9c3..1522817443 100644
--- a/L2J_Mobius_7.0_PreludeOfWar/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_7.0_PreludeOfWar/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7371,23 +7371,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7540,8 +7537,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7564,20 +7559,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7600,8 +7581,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_8.2_Homunculus/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_8.2_Homunculus/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index a9c477f7fb..c6ee2998f6 100644
--- a/L2J_Mobius_8.2_Homunculus/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_8.2_Homunculus/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7473,23 +7473,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7642,8 +7639,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7666,20 +7661,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7702,8 +7683,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}
diff --git a/L2J_Mobius_9.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java b/L2J_Mobius_9.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
index f6308fd98e..97fe2a2655 100644
--- a/L2J_Mobius_9.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
+++ b/L2J_Mobius_9.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/model/actor/instance/PlayerInstance.java
@@ -7499,23 +7499,20 @@ public class PlayerInstance extends Playable
 		if (store)
 		{
 			storeSkill(newSkill, oldSkill, -1);
-			
 			if (CommonUtil.contains(DUAL_CLASS_SKILLS, newSkill.getId()))
 			{
 				final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-				if (!dualClassSkills.contains(newSkill))
+				for (Skill dualSkill : dualClassSkills)
 				{
-					for (Skill dualSkill : dualClassSkills)
+					if (dualSkill.getId() == newSkill.getId())
 					{
-						if (dualSkill.getId() == newSkill.getId())
-						{
-							dualClassSkills.remove(dualSkill);
-							break;
-						}
+						dualClassSkills.remove(dualSkill);
+						break;
 					}
-					dualClassSkills.add(newSkill);
-					getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
 				}
+				dualClassSkills.add(newSkill);
+				getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
+				
 			}
 		}
 		return oldSkill;
@@ -7668,8 +7665,6 @@ public class PlayerInstance extends Playable
 	 */
 	private void restoreSkills()
 	{
-		final List<Skill> dualClassSkills = getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, new ArrayList<>());
-		
 		try (Connection con = DatabaseFactory.getConnection();
 			PreparedStatement statement = con.prepareStatement(RESTORE_SKILLS_FOR_CHAR))
 		{
@@ -7692,20 +7687,6 @@ public class PlayerInstance extends Playable
 						continue;
 					}
 					
-					if (CommonUtil.contains(DUAL_CLASS_SKILLS, id) && !dualClassSkills.contains(skill))
-					{
-						for (Skill dualSkill : dualClassSkills)
-						{
-							if (dualSkill.getId() == skill.getId())
-							{
-								dualClassSkills.remove(dualSkill);
-								break;
-							}
-						}
-						dualClassSkills.add(skill);
-						getVariables().set(KNOWN_DUAL_SKILLS_VAR, dualClassSkills);
-					}
-					
 					// Add the Skill object to the Creature _skills and its Func objects to the calculator set of the Creature
 					addSkill(skill);
 					
@@ -7728,8 +7709,10 @@ public class PlayerInstance extends Playable
 		// Learn known dualclass skills.
 		if (isDualClassActive() || !isSubClassActive())
 		{
+			final List<Skill> dualClassSkills = new ArrayList<>(getVariables().getList(KNOWN_DUAL_SKILLS_VAR, Skill.class, Collections.emptyList()));
 			for (Skill skill : dualClassSkills)
 			{
+				removeSkill(skill);
 				addSkill(skill, true);
 			}
 		}