Duplicate Npc

Originally posted by [b]Dkanze[/b]
http://www.eathena.ws/board/index.php?autocom=bugtracker&showbug=2014

So. We have one NPC, than we duplicate NPC with standart methods, for example for 5 times.
Then, load this npc in to server.
All of these we can see.
Then try to unload npc one by one with "right-click-menu".
On the 2-3 NPC we get map server crash. Guess why?

PS. unloadnpc command unload all duplicated NPC, while "right-click" not.