I think it would just require generating the table of hashes once on each type of hardware in use (whether CPU or GPU), then doing the lookup only in the table that matches the hardware that generated it.
To re-do the hashes, you would need to run it on the original offending photo database, which -- as an unofficial party doing so -- could land you in trouble, wouldn't it?
And what if you re-do the hashes on a Mac with auto-backup to iCloud -- next think you know the entire offending database has been sync'd into your iCloud account :-/
And what if you re-do the hashes on a Mac with auto-backup to iCloud -- next think you know the entire offending database has been sync'd into your iCloud account :-/