He's probably got a dual monitor setup on it and has a main monitor set up as a clone, all add to the theme of the game i suppose.
i'd hate to think how much thats worth with regards to man hours and material.
Wow... im blown away, and I havent ever played Doom. That is truely a work of art. Im sure money and time wasnt the issue, as a married man this is probably his hobby. Its unbelievable though..