Weird

Maybe plug it back in and then unplug the other one?
You’ll have an extra data point at least…

There are leads to reverse, but they’re a bit of work to access. Remove the cap/top and take the sock off. This will allow you to access the connections for the sub amp. If I can do it, it’s not difficult. Hardest part is getting the sock back on the same way it was from the factory. 

RVpiano is like any RV, he keeps on trucking.

IMO, the usually level headed Jason is wrong here…do not attempt to disassemble the speakers!  Newbee is on the right track.  This is about room interaction and too much low bass energy when both active woofers are powered up. Try reducing the levels by a lot on both to see if you can get back to the same overall bass performance with both working as you have with one turned up higher. If you succeed with this you should benefit from lower distortion and more uniform response across seating positions. 

I may have solved the problem but I’m not absolutely sure.

I had the left subwoofer plugged into a cheap power hub and the right subwoofer plugged into the wall. Ironically it sounded better with the right power cord (the one plugged into the wall) pulled out.

I’m listening now with both plugged in the wall and I THINK it sounds fine.