pfSense » pfSense Plus

You have to force your browser to resubmit the form when in that state. I'm not sure I'd classify that as a bug since it's doing what you told the browser to do, resubmit the form and create the certificate again.

Could maybe try to handle that better but there isn't anything technically invalid against having multiple certs in the list with the same name/subject, and it's common for certain use cases to do that.

So rather than any kind of input validation to prevent this, it would have to do some other kind of page redirect via GET after creation so the browser wouldn't be in a state where a refresh would perform another POST. Then it would have to worry about passing along the result success message string in a safe manner.