This is not used /created by the current app version.
Users who have had/still have installed older versions of Tinderbox may have this support folder:
~/Library/Application Support/Tinderbox/backups/
If not using older versions this folder and its contents may be deleted. It is effectively deprecated. The task is taken over by versioning built into the app (and do not overlook time Machine as another form of recovery back-up).
To make it easier for the general Mac user to access Tinderbox's support folders, the Help menu's 'Reveal Support Folder in Finder' option will open the folder in a new finder window.