Multiple Entry Points
Siloing or grouping similarly themed pages together on a Web site is one of the most important factors in supporting keywords to achieve higher organic rankings. One thing that can have a negative impact on siloing is having the same page render under multiple URLs. Typically this happens when sites include tracking codes in the URLs to track their visitors' paths for analytics purposes. The same physical page is rendered, but a different tracking code is appended, creating a new URL. This of course can cause some nasty duplicate content issues, especially if your home page or main landing pages have several tracking codes associated with them. As an example, let's say there are three unique URLs that render the same page:
The end goal is to eliminate every version of this page except for one. Ideally this will be the page that receives the most traffic. If you have an analytics account installed on your site, it can provide you with information regarding which version gets the most hits. Having analytics installed pretty much eliminates the need for any other tracking methods, so you probably won't be missing anything if you get rid of the URL tracking codes. If we were to eliminate the tracking code from each of the above page names, we would be left with one page: page1.php. By default, all versions of this page are now consolidated into one URL that will receive all traffic, conversions, links and PageRank.
If you don't have analytics installed it's a slightly different implementation but the end result is the same. Simply review the data collected from your tracking codes and find the one with the most traffic/conversions. This page should be used as your main page. Next, you'll want to set up 301 permanent redirects for the other versions of that page and point them to the new main page. This will take care of any duplicate pages floating around in the indexes and will consolidate and transfer any link popularity and PageRank the other versions might have had to the new main page. You will need to set up cookies on your server as well to catch the analytics information. The same data that was collected in the tracking codes is now stored on the user's machine instead of appending to the URL.
Understandably, some sites are going to have problems converting their tracking codes into cookies due to CMS template restrictions or other technical road blocks. If this is the case and you have analytics data, sift through it to find the version of the page that receives the most traffic/conversions. Use this as your main page and 301 permanent redirect all the others to the main version.
Either way you do it, getting rid of URL tracking codes will eliminate duplicate content issues, PageRank will be consolidated, and your Web site's themes will be stronger, which could mean higher rankings.