Redundant Web Server Helpers

I hesitate to call this a bug - but while trying to setup a mirror domain on a new system, it seemed logical the best way to duplicate the domain on the new server would be to restore from domain backup. This process is blocked, however. It seems that no matter what option is picked, the restoration fails because “DNS already exist”. The DNS exist because the Name server is a slave to the primary system. I have tried to uncheck the option to backup and restore DNS as well as told the new server NOT to build DNS by default, yet still the problem persist. Please advise if there is any way to accomplish such a task from the virtualmin application. Because time is of essence, I very well may do this process manually - but for future reference I’d like to better understand what is happening here.