The only way you could do something like that would be with a monitor with picture by picture support. You'd then need the necessary input connection options on the monitor to support your graphics card outputs. I expect HDMI would be a common option on PbP supporting screens. Obviously the resolution output of each half of the screen would be limited. Maybe on something like the LG 34UM95 that would be reasonably usable as well as it's got s nice wide resolution.
CCTV ones work that way because the signals are combined and processed into that form before being sent to the monitor. What the OP wants is just not possible without some form of electronic combining and processing of the signals before being sent to the monitor. Frankly that would cost more than a second monitor.
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