I suspect it pertains to the fact that’s most RNGs tend to be pseudo-random number generators that maintain an internal state. Each call of the RNG mutates the internal state. If you have two processes, one calls the RNG 2 times and the other calls it 5 times, the process states will have diverged and the simulation is no longer consistent between them. This is true even if the simulation ends up using 1 value out of those RNG calls, because the RNG state itself is implicitly part of the simulation.
