I have checked with other headphones,and my small 2:1 home theatre also complies the existence of the problem.
Moreover when I check my sound system through Pulseaudio "test sound" utility, I can see there are six buttons shown, whereas I should only have lest and right buttons as I have 2:1 home theatre (connected on the rear audio port) and a normal headphone (connected on the front side).
I also have jackd installed and configured to run along-with pulseaudio.
On the Screenshot you can see Jack Sink is working with five output ports where I should only have Front Left and front right.
