I have Zenbook Duo 14", and second screen has some issues.
1. Bottom screen can act as touchpad mapped for both top and bottom screen at the same time - bottom part is for itself, while top part is for the top screen. Sometimes it acts as a touchpad for only top screen.
2. When main screen fades to black due to inactivity, bottom screen is still lit, reducing power saving efficiency.
3. I tried installing screen calibration utility, but it looks like it thinks that both screens are the same device. When it's fullscreened, it shows 2 top dots on top screen, and bottom dot at bottom screen, making it impossible to calibrate due to bottom screen touch mapping as top screen.
4. Button to disable 2-d screen, as well as button to swap tasks between screens do nothing.
5. Looks like I can't edit brightness of 2-d screen - it looks dim.