That’s the point, reality isn’t deterministic,so you can’t really use deterministic math to describe it. That’s just an approximation, regardless of errors in the simulation. That’s also why you run Montecarlo simulations, not to even out simulation errors, but to compute as many probable outcomes as possible and then have a probability distribution that represents your best bet at guessing the non deterministic reality that you are trying to predict. If you “run” reality twice your not gonna get the same result