I think everyone has one hang lower than the other, Me, my right one.
Now back to the bikes. Yes, they often hang uneven. You can try loosening all the mount bolts on one side from the head back. Now get your mufflers as even as you can, now tighten the mounts from the rear forward to the head. If this helps fine. If not still even do the other side the same way.
If you can't get them the way youy l;ike you can try bending the low side head pipe up, the high side dow, or the other way round, high side up low side down.
Me I don't worry so much. As long as it runs well and nothing falls off, i'm happy.
Leo