Yes the pic shows 2 driver side flywheels. The one on the left shows how much material was taken off vs. the flywheel on the right.

I needed to compare the weights of the standard weight billet steel vs. lightened billet steel vs. aluminum 10.5" 130t flywheels. The standard weight and aluminum flywheels are for sale.

The lightened billet steel above is mine to keep as its so f@×king awesome!

Looked at the billet aluminum one I have and turns out it is the passenger side starter style which matches my bell... lucky I guess.

Wonder what happens if you mix them up... if they still catch but not fully or what.

All the ones I've saw for sale seem to be ps style. At least the mp ones like mine.

Lucky for sure!
I would think that if you mixed the flywheels around that the starter gear probably wouldn't catch and worst case the ring gear teeth would end up getting chipped. That results in the engine not starting easily and one would need to flip the ring gear teeth over. I had to do that before on my old 340 small block flywheel with a propane torch, not a fun experience.