Enhance CSPRNG output [duplicate]

If I XOR the output from 2 CSPRNG will the result be better (more random) than the output from either one? Assume one of the PRNG is biased.

• How are they keyed? With two independent keys? Also, if one is a CSPRNG, then it cannot be biased (to be cryptographically secure means that it can't be biased). – D.W. Dec 6 '13 at 1:47

• More generally, if you XOR the streams of two independent random number generators together then the result is as strong as the strongest of the two. $\;$ – user991 Dec 5 '13 at 8:20