Can you plug two PPPoE connections into a switch and Layer-2 bridge, and then do authentication to the right connection at the other end?

We are using a Ubiquiti PowerBeam AC as a transparent Layer-2 bridge to pull an internet connection from about 300m down the road.

The connection uses PPPoE for authentication, and we're doing the auth on our side of the bridge.

However, what if we want to provision two internet connections at the other end, both using PPPoE?

We could plug them into a switch at the remote end, and then pass them over the PowerBeam bridge.

However, how do we distinguish them on our end? (I.e. we currently just punch in the PPPoE username/password given by our ISP. If we have two such connections ending in a network switch, how does the PPPoE connection know which to use?)