It's so sad to say, but I've found a way to actually duplicate items.
This exploit allows you to duplicate your character, so you can kill it and take all the stuff that's in it. More detailed informations can be found in video posted below (it's not a public video, so only people that have a direct link can watch it).
It works almost every time, couple of my buddies tried to do that and they succeeded. It's more of a technical problem so I can't tell what can possible fix that, expect disabling ESC button while connecting to the server.
If there's more feedback needed - post it under this report.