The Wilco 737 (assuming this hasn't been changed with the Evo version, we tested only the original one) use the same door command (Shift+E 2) for both cargo doors and for the catering doors, and so it's normal they would be handled and requested together.
It uses the default Shift+E command for the main door and can't open the rear door, I've checked the GSX file and is all correctly configured as such.
In any case, as explained several times on the forum, whenever you seems to have a problem with an airplane that you can't seem to open its door, it would be enough to put the following code:
code = 0
in the relevant Exit in the GSX.CFG, this will force GSX to ignore that door open/closed status.