However, having one and not the other isn&#x27;t totally useless.<p>Having the browser be able to track and tell me that &quot;Though we aren&#x27;t sure this is actually google.com, we do know that the exact same cert has been used the last 50 times you visited this website&quot; is something I&#x27;d consider to be useful.  (Actually, telling me if it changes would be the useful bit).<p>That would be at least be useful for self-signed certs (though those aren&#x27;t really needed in light of Let&#x27;s Encrypt...)