Multiple Domains and Google

If I own two domains: domain1.com and domain2.com and point them to the exact same content on the exact same server would Google potentially punish me for duplicate content due to the domain names being different?

For example,

http://www.domain1.com/index.php and
http://www.domain2.com/index.php would be serving the same document from the same server.

Secondly, depending on the answer above, would Google see the following eight links as different, possibly as duplicate content (even though the same content is being served from the same server?)

http://domain1.com/index.php
http://domain2.com/index.php
http://www.domain1.com/index.php
http://www.domain2.com/index.php
http://domain1.com/
http://domain2.com/
http://www.domain1.com/
http://www.domain2.com/

Lastly, are the two following links considered different pages to Google?

http://domain1.com/index.php&id=1
http://domain1.com/index.php&id=2

You should 301 redirect one domain to the other domain so that they don't hurt each other's rank.

So when all is said in done, the optimal goal would be to have one link that everyone uses correct? Having more than 1 splits PR and relevancy too much?

That's the general idea, yes.