Surface duo android operating system and not microsoft

Can I use app inventor 2 for the surface duo in future?

I don’t see why this wouldn’t be possible. The App Inventor website supports touch events, so you can design and code on a tablet. A common demo I give is split-screen Safari + companion running on an iPad, but you can also do this with an Android tablet or Chromebook. I imagine the Surface Duo wouldn’t be much different in this respect.

Can I use multiple screens with app inventor
2 screen on 1 screen..
I want to look 2 screens on the same time.

If by two screens you mean view App Inventor screens at a time, no that's not possible. You can run App Inventor the website and the App Inventor companion app side by side on most tablets, which does allow you edit and test at the same time, but there is no way to have two screens open simultaneously.