Best way to recover/restore Time Machine Backup to a second HD?
Well... the answer when you posted this question WAS yes.  You could just turn off auto-backups and copy the backups folder to a new drive and set Time Machine's prefs to use that drive.  

But if you've migrated to Mojave, good luck. Apple has seen fit to remove that ability from even an admin's hands.  You don't have the ability to modify the Backups.backupdb folder or contents, even with SIP disabled.  

EDIT: I think I found a workaround.  You can't modify Backups.backupdb, but you can delete it and replace it.  Back up your backups, if you feel the need.  Create a folder named "WhosTheBoss" or "ImTheBoss" and put any backups that you want to keep in there (with the same directory structure).  Delete the original Backups.backupsdb folder and make that the name of "WhosTheBoss".  Point Time Machine and/or Migration Assistant to that location and you're good to go.