Yep .. Trainz has supported Matrox dual head displays for a long .
or you can do this
http://www.matrox.com/graphics/surroundgaming/en/home/
Montreal, Canada, August 5, 2008/PRNewswire - Matrox Graphics announces new triple widescreen modes for the TripleHead2Go Digital Edition: 3x1680x1050 and 3x1440x900. The new modes allow gaming enthusiasts and professionals to benefit from the advantages of widescreen technology across an astonishing desktop set-up.
Trainz support listed for Dual and Triple head setups -->
http://www.matrox.com/graphics/surroundgaming/en/games/#