I had one of these, and once it got a curse of krong, I made another one to replace it. I kept the old one in my inventory to sell once i got to a shop. But, since the stats were different (resists/dmg bonuses), I wanted to try another. Instead of making another one, it made a second of the cursed one in my inventory, with the (2) in the corner. However, the stack cannot be separated and any further attempts while it is in the inventory to make it cause the shields to be exactly like that one.