2013-03-22 05:15:14 [SEVERE] Could not pass event ChunkLoadEvent to DragonAntiPvPLeaver v1.9.5.2
org.bukkit.event.EventException
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
	at net.minecraft.server.v1_5_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:139)
	at net.minecraft.server.v1_5_R1.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:85)
	at org.bukkit.craftbukkit.v1_5_R1.CraftWorld.getChunkAt(CraftWorld.java:119)
	at org.bukkit.craftbukkit.v1_5_R1.CraftWorld.getChunkAt(CraftWorld.java:494)
	at org.bukkit.Location.getChunk(Location.java:73)
	at com.forgenz.mobmanager.limiter.world.MMWorld.updateMobCounts(MMWorld.java:166)
	at com.forgenz.mobmanager.limiter.world.MMWorld.updateMobCounts(MMWorld.java:125)
	at com.forgenz.mobmanager.limiter.listeners.MobListener.onCreatureSpawn(MobListener.java:202)
	at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
	at org.bukkit.craftbukkit.v1_5_R1.event.CraftEventFactory.callCreatureSpawnEvent(CraftEventFactory.java:227)
	at net.minecraft.server.v1_5_R1.World.addEntity(World.java:925)
	at net.minecraft.server.v1_5_R1.SpawnerCreature.spawnEntities(SpawnerCreature.java:159)
	at net.minecraft.server.v1_5_R1.WorldServer.doTick(WorldServer.java:168)
	at net.minecraft.server.v1_5_R1.MinecraftServer.r(MinecraftServer.java:554)
	at net.minecraft.server.v1_5_R1.DedicatedServer.r(DedicatedServer.java:225)
	at net.minecraft.server.v1_5_R1.MinecraftServer.q(MinecraftServer.java:476)
	at net.minecraft.server.v1_5_R1.MinecraftServer.run(MinecraftServer.java:409)
	at net.minecraft.server.v1_5_R1.ThreadServerApplication.run(SourceFile:573)
Caused by: net.minecraft.server.v1_5_R1.ReportedException: Adding entity to track
	at net.minecraft.server.v1_5_R1.EntityTracker.addEntity(EntityTracker.java:115)
	at net.minecraft.server.v1_5_R1.EntityTracker.addEntity(EntityTracker.java:89)
	at net.minecraft.server.v1_5_R1.EntityTracker.track(EntityTracker.java:24)
	at net.minecraft.server.v1_5_R1.WorldManager.a(WorldManager.java:18)
	at net.minecraft.server.v1_5_R1.World.a(World.java:959)
	at net.minecraft.server.v1_5_R1.WorldServer.a(WorldServer.java:758)
	at net.minecraft.server.v1_5_R1.World.addEntity(World.java:952)
	at net.minecraft.server.v1_5_R1.World.addEntity(World.java:897)
	at com.topcat.npclib.DragonAntiPvPListener.NPCManager$WL.onChunkLoad(NPCManager.java:110)
	at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
	... 27 more
Caused by: java.lang.IllegalStateException: Entity is already tracked!
	at net.minecraft.server.v1_5_R1.EntityTracker.addEntity(EntityTracker.java:100)
	... 39 more