Its possible. I installed an amp using the same reciever and all 4 channels were out of phase. YPAO confirmed over and over. It didn't sound right. I knew it wasn't the(my) wiring so I swapped pos/neg at two of four speakers and walla.YPAO confirmed. Changed the other two and it sounds right.
Its internal in the reciever or the amp. Not sure which. Never will know.