I'm running Mojave 10.14.2 on a late 2014 Mac Mini with two displays. They are mirrored and I cannot find a way to end that.
Mac mini 2018 or later
Command-F1
or go to System Preferences->Displays->Arrangement and turn off mirroring.
Command-F1
or go to System Preferences->Displays->Arrangement and turn off mirroring.
Thank you. It worked. But I remain confused because that option was not available during my two-day efforts to solve the problem. It was there three days ago when I chose it in order to see what mirroring does. Then it disappeared. Shutting down and restarting the computer didn't bring it back. After reading your reply I decided to give it another try and was amazed to see the mirroring option had returned. I removed the checkmark and everything is normal again. So THANK YOU VERY MUCH!
I'm glad that you got it working.
Mirroring two displays
