See Theorem 6 of the GGPR'12 paper, its on page 26. https://eprint.iacr.org/2012/215 https://eprint.iacr.org/2012/215 which addresses the rerandomization of the

See Theorem 6 of the GGPR'12 paper, its on page 26. https://eprint.iacr.org/2012/215 https://eprint.iacr.org/2012/215 which addresses the rerandomization of the proofs in the prover that result in them being a uniform sample of all acceptable proofs.