Think you have to begin a restore process first. Moodle then looks for valid backup files upon uploading (1.9 backups use .zip, 2.x backups use .mbz).
So, create a hidden category called 'restores'. One hidden minimal course called 'restores' - don't have to assign anyone as teacher nor any students if you are the system admin. Think the course is necessary to get to the 'Restore' link in the context to be at the course level.
When you are in the restore process you'll have options on cat to restore to as well as other options for the course. As with many things Moodle, too many options to list in an email. Just don't replace the hidden/no user 'restores' course - assign to category desired, change title, etc..
I usually create a hidden System Admin category/course that has system admin links (like a link to force the running of the cron job) and other system admin tools but also use it for restoring courses to new courses in other categories.
'spirit of sharing', Ken