If "Backup Versions Auto Download" is set to true on the Admin > General > Ops Manager Config > MISCELLANEOUS tab, then the backup daemon automatically downloads all older major versions of the software.
In my opinion, it would be better if you could either select the version/s which you want or it only downloaded versions equal to or higher than your current version.
All the old versions take up disk space and can only be deleted if the setting is changed to false.
thanks