[@sambauers Participant 16 years, 2 months ago]

The password hash is always unique, even when the password is the same, that’s the nature of phpass hashes.

I joined and logged in to your site. I edited my profile and indeed the password stopped working. First things first, try deactivating the signatures plugin you are using and see if the problem still occurs. If not that’s the culprit and it needs to be modified by the plugin author to stop this behaviour.