There's not just two AoAs though, one per wing; there's a whole gradient of different AoA values going down both wings, like how the speed of a turning record is continuously variable from the inner to outer edge.

It helps to think of the two wings combined into a single long wing (like a B2 bomber, which does actually have this design), then imagine that banking into a turn -- it's different values along the entire surface.

A single AoA value taken from the center of this long combined wing, i.e. the fuselage in a typical jetliner configuration, should be sufficient for the purposes of determining if the plane is about to stall. If you really need the AoA values at all points along the wings, you can calculate them by combining the center AoA sensor with the roll angle.

This logic applies to airspeed as well (it varies continuously along the entire wing surface when the airplane is banked into a turn), and note that airplanes only have one cluster of pitot tubes, which are located on the fuselage.