If the same thing has happened on 2 different trailers, I does sound like the BC.
But, just for the record in case it is relevant at all, we had really "grabby" brakes on a previous TT we owned which we bought new. It was terrible at low speeds, especially in CGs with gravel roads and the slightest touch on the brake pedal locked the TT brakes up. Complained and complained to the dealer and all they would say is that it was our BC. So we replaced it with an Prodigy P3 and nothing changed. Things went on for a year like this and we sent a letter in writing to the dealer about the problem and they finally reluctantly agreed to re & re the brakes. Got it back a week or two after the warranty expired and they said they found what they claimed was cosmoline coating everything and they said it was the factory's fault. It was probably leaking seals and grease contamination though. They found warped drums and replaced those along with the brake pads. After that the brakes worked perfectly as they should have all along.
Leaking seals on new TTs does happen. Found it in our current TT at less than a year old. 'Nuther story for another day tho...