@thatmattrogers said:

TH2go seems to only display as a single screen

As @Skulpture wrote, this is the expected behavior. It's for Isadora 3, so the exact names and appearance of things might have changed from what's in the article, but the general information/idea explained under the heading "For users working with a Matrox TripleHead or DualHead only" in this support article of ours about working with multiple displays might still be helpful to you.