Going into trade saves the items on a character, and closing trade reverts them back to how they were at the save. We all know this from the waypoint duping method and the socket/personalize one. All that was needed for a working dupe method was a way of getting an item onto the ground while in trade. Obviously dropping items manually or with packets or all sorts of obvious exploits like that immediately click the client. Here's the key point Imbuing an invalid item will make it drop at your feet. That's all there is to it. Go to trade, pick up the item on your cursor (hence sniffing the item code in the 0x17 packet), and send an imbue packet for that code (0x38 packet). An exact copy of the item falls to the floor at your feet, and when you close trade, the original remains in your inventory.