It appears this doesn’t happen with Firefox, unless I created the certificate so it doesn’t apply to that domain. Not sure how that works. (Guide + openssl pkcs12 -export -clcerts -in client.crt -inkey client.key -out client.p12)
I’m using Safari 9.1.1 (11601.6.17) in OS X 10.11.5 (15F34).
I had set the https server to request a client certificate for a first time visitor. However, you shouldn’t be continually asked to supply a client certificate.
So, I turned off the option in the https server where it requests a client certificate. The popups should be gone now. However, let me know if they still come up.
Cheers
P.S I never really looked into the benefit of having to request client certificates in the first place, simply because B&C Explorer doesn’t deal with sensitive client information.