I was recently participating in a CTF with a challenge that required contestants to find two
md5 hash, and that got me thinking about how that could be a potential vulnerability in some systems (though not necessarily a large one).
But that could be easily avoided by using multiple types of hashes of, for example, a user's password. That way, if one collision was to occur, the other hash types would be able to determine that it's not the same password. Has this ever been put into practice, or is the chance of a hash collision so rare that it doesn't really matter, and it's not worth the extra computing power?