iis - Separate Certificate by Subdomain (With multiple IPs)

Note: Yes, I realize this problem is easier to solve by just using 1 multi-domain or wildcard certificate.

I wish to have an ASP.NET site running on IIS with 2 SSL domains sharing 1 web application but using separate certificates. Assuming I have 2 certificates, this can be solved on IIS7 as follows:

Web Application1:
Binding 1: http, 80, IP Address *, Host Name *
Binding 2: https, 443, IPADDRESS1, using CERTDOMAIN1 (DOMAIN1 resolves to IPADDRESS1)
Binding 3: https, 443, IPADDRESS2, using CERTDOMAIN2 (DOMAIN2 resolves to IPADDRESS2)

That is to say, 2 certificates and 2 ip addresses, but both mapped to the same web application.

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In IIS6, the closest I have been able to come to this configuration is:
Web Application1:
Binding 1: http, 80, IPADDRESS1
Binding 2: https, 443, IPADDRESS1, using CERTDOMAIN1 (DOMAIN1 resolves to IPADDRESS1)

Web Application2:
Binding 1: http, 80, IPADDRESS2
Binding 2: https, 443, IPADDRESS2, using CERTDOMAIN2 (DOMAIN2 resolves to IPADDRESS2)

That is to say, 2 certificates and 2 IP addresses, 2 web applications, both mapped to the same file location.

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The IIS6 solution is not optimal. Even if sharing an application pool, there are still costs associated with running the same site as two applications. Is upgrading from IIS6 to IIS7 a legitimate way to resolve this problem? Is there an IIS6 way to map 2 IP addresses within the same web application to different certificates?