Your Tetra Whisper air-pump is working fine. What I see is a slight kink in the airline in the lower picture. That is enough to un-equalize the air pressure.
Yes, theoretically, if both adjusters are set the same, the pressure and bubbles should be the same. But those are cheap adjusters and you have to set them by feel. They are the ones I'd recommend. They're just like the ones I use.
Close #1 off all the way. Open #2 as far as you can, judging by the bubbles. Then open #1 till they're equal. If they still are not equal, reverse the numbers and try again.