One PC, two monitors, two keyboards, two mice.
Trying to implement how to have only one on at a time. Reverse KVM Switch? Most have timeout, can't have that. Relay to power cord of second monitor work?
Video wise - If you have 2 video outputs it is easy - clone the desktop and run the 2 monitors. I have a situation where on an old system I have some VGA splitters to extend monitors via long VGA cables.
The easy way to have more than one keyboard or mouse if near the physical PC is just add USB keyboards and mice. Thay all work together. My situation has a keyboard and mouse working the one PC from 2 other locations 100 metres away by using a LAN USB extender. This just extends the USB over a Cat 5 or 6 cable. The hardware (a "transmitter" and "receiver" to covert the USB to go up the LAN cable and then convert back to USB) cost about $40. That and a LAN cable is all you need. In my case as mentioned above I have the video extended over a cable and it is fine to see what I am controlling.