Splitting the PRNG would provide resistance to tampering by walking into walls and the like, but it would also reduce the avalanche effect of code changes, hidi

Splitting the PRNG would provide resistance to tampering by walking into walls and the like, but it would also reduce the avalanche effect of code changes, hiding inaccurate probability distributions (e.g. if a polymorph potion turns you into a yeti the next spawned monster is likely to have low hit points) that would cease to change drastically as PRNG calls are added or removed anywhere.