www.makemkv.com

The newer versions have a huge drawback for me:
Whenever you start a new makemkv instance while using two BD drives the drive that is in use is being interrupted. There is no way to select the drives in advance as it used to be. I hope this will be fixed (MAC).

This should apply to the Mac version, as well?

Check 'Ask for single drive mode' under Preferences > IO tab.

Thanks, that solved it. Just confused by the term single drive mode for multiple drives!