@ThatCrazyDude
Windows + P displays a menu from which you can select Display 1, Display 2, mirror 1=2, or Extend — use both.
But you can keep pressing Win + P and it will start switching these options.
You can also do this from a script, your System32 should contain this tiny utility DisplaySwitch.exe — you can e.g. run it with "/Internal" to use only primary display display.