I theorized the other day that character data is saved when the player exits the game, and not when their combat-log entity leaves the world.
Originally I tried cuffing the player and grabbing some gear, but did not uncuff the player before his entity was removed. This resulted in him spawning as a new character the next time he joined(The combat-log entity was removed from the world and never created a corpse; there are other reports about this)
On the second test we had a third member handle cuffing and uncuffing; We were successfully able to take the entire inventory of the member this way, and have him spawn with all his gear in tack; duping it.
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This method of duping will continue to work for a long time, unless character saving happens after the combat-log entity is removed; or you remove the ability to cuff a logged out player.