windows server 2008 - Adding multiple websites with different SSL certificates in IIS 7

I'm having troubles using SSL for 2 different websites on my IIS 7 server.
Please see my setup below:

website1: my.corporate.portal.com

SSL certificate for website1: *.corporate.portal.com

https/443 binded to my.corporate.portal.com

website2: client.portal.com
SSL certificate issued for: client.portal.com
When I try to bind https in IIS7 with the client's certificate, I don't have an option to put host name(grayed out) and as soon as I select 'client.portal.com' cert, I'm getting the following error in IIS:

At least one other site is using the same HTTPS binding
and the binding is configured with a different certificate.
Are you sure that you want to reuse this HTTPS binding 
and reassign the other site or sites to use the new certificate?

If I click 'yes' my.corporate.portal.com website stops using the proper SSL cert.

Could you suggest something?

Answer

Implementing Elastic Load Balancing for the Amazon instance solve the issue (http://aws.amazon.com/elasticloadbalancing/)