Why would you want to do that?

That would make much more difficult (if not impossible) to guess the internal state of all RNGs.

You can't guess the internal state of a CSPRNG based on the output. That's what makes it CS. The only way to get the internal state is to break the OS protection and look at the memory directly. And if the attacker can do that, then they can do it for the multiple PRNG version too.

I misunderstood the context in your replies. We were kind of talking about different topics.