If you have a hash collision in a cryptography context, you have a broken system. E.g. MD5 became useless for validating files, because anyone can create collisions without a ton of effort, and thus comparing an MD5 sum doesn't tell you whether you have an unmodified file or not.

On a hash map collisions are part of the system. Sure, you'd like to not have collisions if possible, but if not then you'll just have two values in the same bucket, no big issue.

In fact, having a more complex hashing algorithm that would guarantee that there are no collisions will likely hurt your performance more because calculating the hash will take so long.