Two plugs controlled by one switch
This sounds like a standard "3-way" switch configuration. Each switch has a "common" terminal and 2 "carrier" terminals. Power comes into the switches on the common terminal of switch "A," travels between the switches on the carriers, then travels to the load (your wall receptacle) from the common terminal of switch "B."

3-way switches can be wired with the supply power coming into one of the switch boxes, or with the supply power coming into the load box (your wall receptacle) and traveling into the switches from there.

If the line voltage comes into the receptacle box, you can easily rewire it so that one socket is always hot and the other is switched. You would just break the metal tabs connecting the two sockets, and pigtail one of the sockets to the incoming hot conductor, while leaving the other socket wired to the common wire returning from switch "B."

If line voltage comes into one of the switch boxes, then you would have to run an additional cable from that switch box to the receptacle box.