Intriguing question, I must say. First a bit of history: even though F. Sarabia was born in the Laguna region and he started flying there, he later moved to Chiapas where (with his brothers) he started an airline ("Compañía Hermanos Sarabia") based at Tuxtla Gutierrez, which apparently played an important role in the development of that region. You can read about it here:
So, as you can see, both places have a valid reason to name their airport after the man. However, even though they usually refer to TRC's airport as "Francisco Sarabia", apparently the one that is really, oficially called that (at least by world aviation organizations) is TGZ.
If you follow these links, you can find the Mexican government's aviation airport authority refer to both airports as "Francisco Sarabia". Here's the link for TRC: http://www.asa.gob.mx/main.php?ira=aeropuertos&grupo=Grupo%20Aeroportuario%20Centro%20-%20Norte
and here's their link for TGZ: http://www.asa.gob.mx/main.php?ira=aeropuertos&grupo=Grupo%20Aeroportuario%20ASA%20Corporativo
BUT any other aviation literature that I've been able to find (ICAO codes, my Jeppesen route charts, and anything from international aviation organizations or associations) refer officially to TGZ as "Francisco Sarabia" and to TRC as "Torreon International".Even the database used by the X-Plane flight simulator program to load the airport you want to fly from/to refer to TRC as "International" and TGZ as "Francisco Sarabia". I'm sure the situation with MS
Flight Simulator is the same.
So, there you have it. I was not able to answer your question 100%, but at least I kept you entertained for about three or four minutes.