Question

I want to store my passwords using 2 different hashes (saving 2 hashes for the same password to (slightly) increase security by (almost) eliminating collisions.
first question: is there enough of an upside for this in the first place since collisions are negligible anyway ?
second question: what would the best hashes for this be ? do sha-1 and sha-256 have more collisions than sha-256 and some unrelated algorithm like blowfish ?

Answer 1

I would recommend using a sha1 and not worrying about collisions. The likelyhood of a sha1 collision is 10^-45 (as explained here Probability of SHA1 collisions), so unless you will have billions of users, it will never be an issue.