Welcome to the Q&A Forum

use the rel=canonical on the main page/s to show that they are the original/source/master page of the content. See this helpful guide: http://www.seomoz.org/blog/complete-guide-to-rel-canonical-how-to-and-why-not Don't forget you can also tell Googlebot to ignore certain URL parameters to prevent them being indexed and treated as duplicate content. "If your site uses URL parameters, some of the parameters may be unnecessary for page navigation. Asking Google to ignore these parameters can reduce duplicate content in Google's index and make the site more crawlable." This is done through Google.com/Webmasters - Your Domain - Dashboard - Settings - Parameter Handling.