How to set DSI-0 and HDMI-0 as same output after bootup

We enable two displays HDMI-0 and DSI-0 on TX2.
Use xrandr can found HDMI-0 as primary screen and DSI-0 as secondary screen.

After bootup completely, HDMI-0 auto show left screen and DSI-0 auto show right screen.
We can use below xrandr command to force DSI-0 same as HDMI-0.

xrandr --output DSI-0 --same-as HDMI-0

My concern is how to force HDMI-0 and DSI-0 to show the same screen after bootup without typing xrandr command by hand again?

53216142,

I believe currently this is the best way. An alternative is to use the ubuntu gui to set this config. After using GUI, there would be a config file generated under your home directory and you would no need to configure it every time afterwards.