IIS7.5 How to make a binding for 2 domains, 2 IPs and 2 certificates

Question

I am clutching at straws... hope you can help me with this old server.

I want to bind domain1.com to ip 123.456.7.1 and domain2.com to 123.456.7.2, each with its own certificate. As longs as I configure it for http, there's no issue. My bindings look like this:

          type   hostname       port    ip
site2 ->  http   domain1.com    80      123.456.7.1
site2 ->  http   domain2.com    80      123.456.7.2

But I want to bind a certificate to each site. I use the Certify-the-web installer to do this for me. This results in:

          type   hostname       port    ip
site1 ->  http   domain1.com    80      123.456.7.1
          https  domain1.com    443     123.456.7.1

site2 ->  http   domain2.com    80      123.456.7.2
          https  domain2.com    443     123.456.7.2

Which works fine for domain1, but gives a wrong certificate warning for domain2 (according to Chrome and Firefox it uses the cert of domain1). It has the right certificate selected in both https bindings when I inspect them. I did restart each site in IIS.

What am I doing wrong?

Thanks in advance!