[Mount81]

My knowledge pertains mostly to Windows. Last I knew, in order to "duplicate" screens in Windows, both screens had to be set to the same resolution. Any chance the 720p screen can accept a 1080p signal? Which video output gets the audio can be set in "Sound" within windows. Set whichever output you want to use to "default". In Windows, you can "extend" displays with different resolutions, but I don't think that will help you, since you won't be able to get the same image on both screens. As far as Kodi, without changing settings, I believe it uses it uses whichever display is set to "primary" in Windows, and whichever audio device is set to "default" in Windows. You could buy a stand alone HDMI splitter/matrix, but again, the output resolution from each port will be the same. If you do get a splitter/matrix, I would recommend one with EDID control. Unless your 720p display accepts 1080p, I think you're probably out of luck. Playing back 3d content will only add more problems. I was going to try to use one PC as a workstation (with a 1080p monitor) and also for Kodi MVC (with a 1080p 3d projector). I was going to use a stand alone splitter. The more I thought about it, the more problems came to mind. I ended up buying a cheap dedicated PC for Kodi MVC and continued to use my workstation for only a workstation. PCs for Kodi can be bought cheap and if you don't need 3d, Fire TV Sticks can be bought cheaper. Let me know what you figure out.

As far as I can remember back, I've used my PC with Win7 for my old CRT monitor (definitely something under 720p) and for my FHD TV simultaneously. Of course on different VGA outputs for each. Can't remember how exactly, but I guess it can be configured somehow.  I also don't remember for sure if I ever had the desktop working on both display at the same time, but I'm sure I had a picture (with the wallpaper at least) on the CRT, while I was operating in the desktop on the TV. The rest could be just the question of the proper configuration.