by Ken Task.
Catch 22 - conditional ... are teachers allowed to make backups of their courses? If so, those backups get tagged as private files belonging to the teacher. Those .mbz files are different sizes/names, so contenthash is different.
Admin level user cannot see the private backup files of the course unless they pretend to restore ... that's when Admin level user can see the private files area.
There is a plugin that will help admin - allbackups.
https://moodle.org/plugins/report_allbackups
Check out one of those copied courses to see about the course backups.
'SoS', Ken