Repro video: http://www.youtube.com/watch?v=6XPPcmmEc_0
There are also derivatives of this dupe which require two players acting at once:
1) Player 1 drags item on the ground AT THE SAME TIME as Player 2 right clicks on it to take it. Player 2 will get the item and it will appear on the ground.
2) Two players right click on same item at the same time which gives them both this item.
3) Two players look at container (say weaponholder with single weapon) and press "Take ..." at the same time.