Our house has a large double sided fireplace right in the middle of it. It has a vent above the doors on either side to circulate the hot air, which is not all that effective. I wondered if it would help to have air forced across the firebox and decided to try an experiment. I rigged up a window fan to blow air into the vent in one room.
It actually does help. It makes the living room, on the other side, nice and toasty.
I’ve seen some townhouses near me with a double sided fireplace in the exterior wall! They can enjoy their fireplace from the living room or the deck. Very odd.