I’d like to suggest adding a proper video on/off toggle to the KVM. When video is off, the KVM should fully disconnect the display so Windows thinks it’s unplugged. This is important because Windows will disable HDR on the main monitor if the KVM screen is still detected.
This would work better than using EDID emulators or HDMI splitters, because those usually keep the display “alive,” which causes HDR issues.
So the idea is simple:
Video ON → monitor connects normally
Video OFF → Windows thinks it’s unplugged
This would make HDR setups with duplicate displays way easier to manage.
Keeping the KVM video alive also causes problems with windows continuously discovering then disconnecting the KVM monitor if you have your graphics card to output on Monitor 1 only. I do this as I cannot duplicate the screen due to the KVM not supporting my resolution at 60hz. If I extend the screen that is fine and keeps windows happy but then the mouse pointer sometimes disappears onto the extend display. Easy enough to get it back but annoying behavior. A real Video toggle would solve this issue as well.
I suggest you use the duplicate display settings because the graphics card is capable of outputting different frame rates on different monitors. Even if your GLKVM supports 30Hz and your main monitor supports 60Hz, it will properly push different frame rates to each display without any issues.
I’ve spent hours with 2 different GLiiNET KVM’s trying to get my screens to duplicate. It simply does not work on my setup. It’s an issue with the Nvidia graphics card I use and a lot of research suggests this is a known issue and not restricted to KVM’s. That’s why I use different workarounds. I can extend output to 4 monitors of different sizes without a problem but I can’t even get duplication to work with 2 identical monitors - that was my last test before I gave up.