Can a PEARL control multiple outside/return damper actuators?

Yes.

The PEARL’s (A1) output is just a control signal, so there is no limit to the number of actuators it can be wired too.

Important!

If a single PEARL is being used to control multiple actuators make sure you wire the common (C) wires from each actuator to the PEARL. This is important because common is used as the reference voltage.