If you are 5Km away, drones separated by a few meters might be in the angular range of beam control fast steering mirrors where the beam director would not have to rotate to cover multiple targets. Fast steering mirrors are either voicecoil or piezo driven so they can slew the beam very quickly.
At 5Km, a high speed racing drone moving at 200Km/hr would cover 0.65 degree/sec which is pretty slow for a gimbal. Tracking is implemented by the FSM mirrors which in turn off load any accumulated angles to the gimbal. If you are very close, that is another matter. 2 HEL units spaced several Km's apart might be able to perform mutual protection.