Forces both monitors to display the same thing:

Forces both monitors to display the same thing:

(Fix to play bzflag):
xrandr --output HDMI-0 --mode  1920x1080 --output DVI-0 --mode 1920x1080 --same-as HDMI-0

and put them back again:

xrandr --output HDMI-0 --mode  1920x1080 --output DVI-0 --mode 1920x1080 --left-of HDMI-0