[Kong]

1. Duplicate video on two or more monitors.
A) Using only 1 computer. Use hardware. A VGA splitter or dual video cards or something similar.
B) Using multiple computers. Use netplay. If you have fast internet connection and are geographically close to each other it works. If you are in the same house it works pretty well. Instructions are lacking though so you need to be technically savvy.
2. Two monitors. Unique video on both screens. (I think this is what you are asking for.)
Same instructions as #1 but also the original game must support spit screen. A few arcade games do this. I don't think any console games do but a few were designed to split screen on a single monitor. In that case you could run dual monitor and stretch the single view across 2 monitors to simulate split screen.
3. Adding split screen to a game that did not original support split screen. Not possible.