I found this exploit by accident the other night while testing out persistent items on my server.

I was checking to see if persistent items was enabled and working correctly on my server with an apple before risking my tent. I placed an apple down, shut down the server and re started it. When I saw it had worked i moved on to the tents, I followed the same steps. When i came back on to see if my tent was in place. I saw that the tent was there in place, as well as in my bag still. I thought it was the bug where sometimes 2 people can have the same item at first but then I saw that I had the apple still from my first test. I did the same thing to confirm that what I was doing was the cause. It seemed to be the case.

After talking to the other admins we all seem to agree that what is happening is that when I have the Item in my bag, place it down, then stop the server useing the interface, it appears that the doesnt update the hive info but it updates its local server files. Then when I log back in the old hive data is recovered and my new server item location is used causing the item to be duped.