Filter Dryer

I recently had 3 coils replaced by Company B. After the repair I had a summer tune up and check performed by Company A, an HVAC company I have used for 20 years with very positive results (they were significantly more expensive for replacing the coils). They were very complimentary of the work done by Company B with one exception. Company B installed a filter dryer in my attic. My Trane XB12 outside AC units already have an internal filter dryer. Company A's technician said you do not want 2 filter dryers. When I called Company B, they seemed to agree and said they would be out to remove the filter dryers they installed. This morning I received the following email from Company B: "I discussed your situation with my installer and lead technician, and he informed me it is actually a very common practice we do. We do it to protect our brand new TXV we just installed against any contaminants already floating around in your system. My service manager and I called Trane's head tech and discussed the situation with him and he said he doesn't have a problem with it and has actually recommended it on situations like this." I don't care what the correct answer is. I just want it right. Thank you for your advice.