This method requires at least 2 people, but would be easier to preform with 3.
Character A is the inventory to dupe
Character B is a player wearing nothing at all
Character C is a player who has both hand cuffs and a handcuff key
1. Have A log out of the game
2. Once A has left C puts the hand cuffs onto A's log out entity
3. Character B then accesses A's inventory and moves all the gear to his own
4. Once B has taken all the gear, or about 15 seconds have passed; C uncuffs A