A server restarted and me and my friend logged back in. The friend's game closed (no error) and the server reported that he was kicked out for not responding. I looked around and saw him ducking. (Didn't know it was him as he shouldn't have even been in the game at all.)

Shot him in the head and he fell over. When my friend reconnected, he spawned again on the same spot where I had previously shot him.
Shot him in the head again and he fell over. This time it was a legitimate death as my friend got the "You are dead" message.

Now there were two corpses of him, effectively duplicating the items he had.