Player 1 - serer admin and guy with gear
Player 2 - No gear

Player 1 has the gear and drops it on floor..
Player 2 picks up gear FAST and logs out
Player 1 stays in server and restarts

Player 2 has the gear because he logged out and updated BI servers
Player 1 gets rolled back 30 seconds or so from the server restart - to the point before he gave the gear away

This is copied out of an internet forum after hearing that duping is still very much possible in .53

The method came up in .51 but appears to still work

Link to the thread:
http://www.unknowncheats.me/forum/dayz-sa/129122-0-51-duplication-dont-jell-reem-2.html

Link to the single post that describes this:
http://www.unknowncheats.me/forum/1099541-post38.html

Note this is just a relaying of information I have not resproduced it myself. But I hate duping and want it gone.