I'm assuming your year has the duct down the center of the ceiling. You might pull a vent cover, and using a mirror and a flashlight, look down the duct and see that nothing's overly amiss. Don't be surprised if you see irregularities in the geometry, but hopefully no real obstructions or discontinuities.
Good HVAC design is not something RV's are known for. These systems are notorious for not distributing the output from the HVAC units very effectively. Also, if your coach is like ours, both (in our case three) units feed the duct, which goes the length of the coach, and while their output may be concentrated in the vicinity of the unit, evenly distributing the comfort in their respective ends of the coach is not their forte.
It's too bad they don't put easily adjustable baffles in the main duct, to be able to isolate the output of a given unit to the area where the air comfort is desired. In any case, I'd be surprised if you have a problem, other than being the recipient of the results of the designer's efforts.