Is it possible to tell the source of a backup?
When you set up a backup using the Maintenance plan, it provides a rather complex name for the database backup (example: MovieManagement_backup_2012_02_14_064551_7520824). You can view this by using RESTORE HEADERONLY. Most people don't supply any name at all when running a backup manually. This can be the difference. Other than that, no, I'm not so sure there's anything you can do there.