Pick up and serve yourself!?

[the Langolier]

Another thing, it is possible to change the code of a given item so that is differs from the original, but because each has a different code, the game treats them as two UNIQUE items. They will not even destroy themselves when dropped on the ground together.

AFAIK, doing that would change the item into something else, propably instable and unusable.

(RE: Zenda)
No.

In most instances, this is correct. However, if there is an item that is not perfect quality, the unique item code can be changed by a single value and the "new" item will be identical to the original, but treated as a completely different item. For every item not perfect quality, there is one and only one sister code that can be used to essentially dupe the item - where each item can co-exist. For any other code that you try, the item will indeed be re-seeded by the game. Sometimes it will become another magical item, perhaps a different base type. Occasionally it will be normalized into a magic potion (potion with blue text and unusable) or something else very silly. I assure you, I have seen this effect and have actually done a lot of experimenting with it.