A few years back I had several domains that pointed to the same content. Isn't creating a 301 redirect( I'm not sure what that does) doing the same thing? And doesn't G punish sites for having identical content.
No, it's not the same as having duplicate content. For sites that do have duplicate content, Google will filter out one set from the index.
then i suppose you can change the redirection sites just a little to have google treat each individually....maybe...
Google can handle the 301 redirects. Yahoo is another matter... I have a nasty experience with Yahoo and 301/302 redirects resulting in a complete disappearing from Y's index