I created 2 login pages of same domain.
I put the form name different for 2 forms
I was encountered this issue for a long time. Firefox was kept input values even page reload. Setting autocomplete attribute to off did not solve.
Form caching is a really useful mechanism for the user experience. But, in the small percentage of use-cases like translating values of textboxes or texareas to other language, these gave me headache.
To resolve this, just simply reset the form after page was loaded as
$('form').trigger("reset");