Where are the "backup" files saved in customize? Does anyone know?

I manually replaced my slider with SFTP and THEN installed Customize when it came out. So it has backed up the custom slider as the "original". I'd like to be able to fix that so I can revert to the stock icon as the backup.

I did install the original icons from installer and reverted it that way. But it bugs me that customize thinks my stock slider is a danged fish.

Is it as simple as putting the stock image back in a /backups/ directory somewhere?