Always dupe on a lowbe ( low hp, dep /slay ) using a nuke from a second party slayer. The slayer side must be ran from a separate computer for it must be ran with full connection ( duper is ran on slow bandwidth ). If box'd this would cannot work. ( possible , but difficult ). A side note, you will know that you have duped successfully when your booted to server select. I have many of time loged in the game, and found 2 duped corpses, one at my bind point , another in the slayed zone. If you dupe off a character thats high in level, you will loose experience for how many corpse that have duped, and yes you will still loose experience if you were slayed in the arena.