Well.. I was messing with the packets of replacing one wand with another.. and well noticed they would copy them selves? After a Few seconds they would disapear.. I dunno if this is just a visual bug.. but might be able to turn it into more.
Edit: The way the swap works Say you have a wand in one hand and another in your inventory if you capture the packets of you picking up one wand and replacing it with the one in ur hand. Then resend it.. It dosent do the swap it simply trys to place both items on one slot and this making a temporary visual copy of them.. Altho still might be more 2 it.
Edit2: Another possable idea for item duping.. you know when your reborn and your items have 0 Durability.. and your inventory is full... it kicks the item into that little box.. same sort of box the owl quest comes in.. Maybe capture the packet of you picking up that item from that little box.. and try sending it over and over? Anyone wana test this..?