Hot answers tagged dual-monitor
xrandr --output DP-0 --auto --same-as LVDS-0 You can use xrandr to change your display settings without much effort. Generally I find that it gives more options then GUI tools. You will need to change DP-0 and LVDS-0 to match your display names. Those are mine from my MBP with the external monitor plugged in the display port.
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