I would need to confirm with Nefario that they did once have the assets. I would hate for the codes to be passed around and people claiming double and triple. I'm sure Nefario would find this reasonable.
Any competent person crediting the codes (that would be you) would double check that a code had not been claimed previously.
The only risk of double claims is if you fail at properly doing your part.
*edit* Nefario beat me to it