Fix for "duplicate id" log message when killing big numbers of quest monsters with mass-attacks.

L2_GameServer/java/net/sf/l2j/gameserver/model/quest/QuestState.java

@@ -570,7 +570,7 @@ public final class QuestState
 		giveItems(itemId, count, 0);
 	}
 	
-	public void giveItems(int itemId, int count, int enchantlevel)
+	public synchronized void giveItems(int itemId, int count, int enchantlevel)
 	{
 		if (count <= 0)
 			return;