Mapping seo and other questions

Hi, I need to map about 50 domains to one WPMU Subdomain installation.
Eg. mapped to mapped to and so on

My criteria:
1. Google will not see both and as duplicate contents(hide from google).
2. Users will still see in the browser address bar

Which is the best way to map and redirect those domain names?
If I use "Addon Domain" in Cpanel to achieve this, do I still need to "Add the CNAME pointing to this url" and "add A Record pointing to the IP address of this server"?

Thanks very much in advance.