It would be awesome if Opus had an option when it encounters file name collision, in addition to existing options, have the option to "create backup of overriden file" (or just "create backup") as a checkmark.
If the option is selected, the old file will have {filanemame}.{extension}.bak (backup extension configurable in settings or not if to much of a hassle)
I don't think I ever seen such a feature anywhere!