slapping two displays ontop of eachother

So i read a post the other day about doubling a screens resolution just by offsetting two displays and putting them ontop of each other, but i was thinking it sounded like a poor idea... however, since the main issue right now is latency and getting frame rates up, what about having 0 offset, using low persistance and alternating the two screens frames... effectively doubling the refresh rate? could then have two 60hz displays, when one is off, the other is on, effectively 120hz... so then if you get up to 90hz displays, effectively 180hz? wouldn't that be better?

mind you the video card would have to render frames pretty evenly between the two displays....