I still don't understand, really. You get the numbers that your machine wants/likes/deserves, but we just agree that the machine adds some additional information (the performance name) in front of the number, so we humans have a chance to know which performance it actually is.
In your example or question or game or whatever you had two files which have different names but same numbers. What would happen if someone tried to put these two into the kpabackup? Well, that's up to you guys, if the file import is a sequential process. In my opinion it doesn't require any error handling, because the machine can simply play stupid and first import the alphabetically first performance and then simply overwite it with the later performance file with same number.
I think we don't have to discuss the need to not only make backups of the KPA's current state but also export/import individual Performances and no matter what the limitations of your machine might be, we need a human readable information in the filename, what this file actually is.
Cheers,
Martin
PS: Zappledan, think there's a pretty strong distiction between kipr and kipf files (file suffix).