I've heard that WN at DAL does... but I've never seen it... however, I haven't flown WN in years. I've boarded a SQ flight at SFO that used dual jetways.

I agree that two jetways might not be the norm, but it would be incredible if DFW could innovate this to make boarding/exiting a lot quicker.

AA could board F first through the forward jetway, then J and Y at the same time (the former through the forward jetway and the latter through the aft jetway).

Another thought is that AA could board Y first, J second and F last with assurances that no one would be traipsing through the premium cabins who wasn't sitting there. All through the process, however, F and J pax could board at their leisure through the forward jetway.