I'll let someone else to answer that.
Starfish, I got the item stuck in my inventory about a week after the ladder started, it was when I was muling with friend.
I didn't knew anything about duping then because the last time I played Diablo in B.net was when LoD wasn't even out yet and I was legit. I could have duped then but I thought it was useless since the item always disappeard when I left the game.
