Aside from the problem of interference from another Mavics controller, drone identification is the biggest hurdle.
Controller interference by another Mavic can be reduced by making sure the controllers are separated by at least 10 feet and everyones antenna is pointed in the correct orientation to their drone. If there is even one person using a controller thats putting out a stronger signal than yours, it could interfere with yours and induce loss of control. Happened to me one time, and my Mavic ended up in the bushes.
Identification can be enhanced by using a bright tape or other mark that makes your Mavic different than the others. When flying with multiple drones in the air, I highly recommend LOS at all times, and not FPV. This will bolster separation from other drones and give you better situational awareness.