In versions prior to 3ds Max 9, the Auto-Backup feature would continue saving even if the scene was untouched. Over a long period of time it was possible for the user to return to their computer and have all their autobackup files completely overwritten with the 'latest' scene.
This has been fixed in 3ds Max 9and higher by respecting the scene's dirty flag (scene needs saving). If the scene has not been changed, no backup will be performed.
In addition, the timer will now be reset AFTER the Auto-Backup has completed, giving the user exactly the number of minutes specified as the Auto-Backup Interval to work on the scene before the next saving occurs.
Using the Autosave Core Interface, you can also change the name of the Auto-Backup files to avoid multiple sessions of 3ds Max from overwriting their backup files.