[domgi]

I can confirm that pairing a second Bluetooth unit of AirTurn PED and assign them in different operation modes makes all four buttons A-B-C-D operational in Touch/Pedal Settings!
It could not be verified before by anyone, so it was a 100$ (CAN) test that came out positive.

Good news for some folks, I'm sure!
If you thought  a two-pedal unit would be enough (and found out otherwise), you won't have to spring for the four-pedal unit and try to sell-off the two-pedal unit.

Looks like it would have been cheaper to just get the four-pedal unit in the first place, though...

Yes, that's right, but I didn't like the look of Quad Pedals units (at least from AirTurn), I didn't know more than a double one would be useful at first, was not ready to invest 200$ for a pedal unit in the first place either... and can also add that I can use just one for performance while I use both when rehearsing!
I also thought it would be nice to share that here on the forum, because even Mike from Zubersoft could not confirm a second Bluetooth unit could be paired on a same computer to complement an another one.
Anyways, as for anything, you can do what you want with that information!