There are three different methods.
1) TDMA (Time division multiplexing). Some sync system so only one camera is emitting light at a given time. The Microsoft Azure Kinect uses this with the 3.5mm sync cable, this enables up to 3 cameras to illuminate at different times.
2) Frequency domain. iToF cameras use different modulation frequencies, you can set different modulation frequencies and the signals won't interfere. The other cameras photon's will contribute to photon shot noise. Or randomly change modulation frequencies by a small amount during the integration time, which is supported by some sensors.
3) Randomly change timing during integration time, this is more common with pulsed ToF cameras. Analog devices had an example of this in their booth at CES in 2020.
2) Frequency domain. iToF cameras use different modulation frequencies, you can set different modulation frequencies and the signals won't interfere. The other cameras photon's will contribute to photon shot noise. Or randomly change modulation frequencies by a small amount during the integration time, which is supported by some sensors.
3) Randomly change timing during integration time, this is more common with pulsed ToF cameras. Analog devices had an example of this in their booth at CES in 2020.