Duplicate content penalty with Google

Is .htaccess the simple solution

[Florida88]

We appear to have a Google penalty with a second domain we own that we discovered is pointing to our main site. Thus 2 separate domain URL's with exact content. (IP is same also)

Here is the problem. When you type the second domain address it brings up our main site and the second domain address is "displayed" in address bar. It now has the PR5 our main domain had, but no backlinks. (Main domian has dropped to PR4 from PR5 but has 70+ good BL, and has dropped in Google SERP from 1-3 to 7 -12)

Here's the question: Do we simply add the second domain address to our current .htaccess file for a 301 perm redirect?

Won't this process elimiate the dup content problem and help regain our PR5 to the main site?

Is there anything else we need to do?

Thanks for your help.

[submitx]

yes 301 is the way to do it.