I am encountering this issue in CE1.9.1.
When a User registers (doesn't matter if it's during checkout or from the Create an Account link) the user keeps getting the password mismatch error even though the password is re-entered correctly.
The form validation does not indicate a miss-match, but once a user clicks on Register it returns the mismatch error.
There is no errors in the chrome console...
I found this: "Please make sure your passwords match" - Password error in Checkout with New Registration form
But I don't believe it is the same error.
I need to fix it soon, any help is greatly appreciated!