Use a Dual-Link DVI Splitter for 20$. Its very simple, but i don't now wether it is working with long DVI cables..
cable a type of cable do you use for the long display connection in the other room?
Sorry for my English, i'm learning..
If i use the splitter i will be able to run different resolutions ?
Because my main display is 1920x0180 and the mirror display is smaller.