Update: I think I know why A3 bleeds to the rear; its an audio clip from a video game and it likely contains PL enconded content, doh!
Still, I cant get my own sound from the rear. A2 is just music and comes out of the center. I think Premiere doesn’t enconde PL at all, so the mono channel comes out of the center but that’s normal PL behavior on non-PL encoded sources (throws mono thru center)
So, in short: CANT GET REAR TO WORK!! 🙁