There are two very common duplicate content issues that all Webmasters should check for. Here’s how to find them and how to fix them:
Non-www and www versions of URLs
Find it!
• Search for a URL on your site. Either remove or add the www in front of the URL and sees if it redirects or if you can arrive at both pages. If you can arrive at both versions of the pages, you need to fix the duplicate content issue so users can only arrive at one version.
Fix it!
• Determine which version (the www or non www) should be the canonical or preferred version, for all URLs on your site. Check your link profile to if valuable links have been built to either version. Which version of the pages rank or are arrived at through your site navigation?
• Redirect all non-canonical versions of the URLs to the canonical versions. When done correctly, the user will be physically taken from the non-canonical to the canonical when the search is attempted. Contact your developer for help in implementing this change.
• Check your XML sitemap. Ensure that only the canonical versions of the URLs are displayed to the search engines.
• Set your preferred domain in Google Webmaster Tools. Go to “Site Settings” and then select the option to display URLs as either the www or non-www version.
Trailing slash (/) and non-trailing slash versions of URLs
Find it!
• Most people don’t even realize it, but these two URLs are different pages to search engines: http://www.domain.com/url and http://www.domain.com/url/. The only difference is the trailing slash. Go to a URL on your site and either remove or add the trailing slash. If you can arrive at both pages, this should be fixed.
Fix it!
• Determine which version (trailing or non-trailing slash) should be the canonical version for all of your URLs. Again, check your link profile to see which version of your URLs has the most links, and therefore equity, which versions rank and which versions are in your site navigation.
• Configure your site to redirect all non-canonical versions of the URLs to the canonical versions. When done correctly, the user will be physically taken from the non-canonical to the canonical when the search is attempted. Contact your developer for help in implementing this change.
• Check your XML sitemap. Ensure that only the canonical versions of the URLs are displayed to the search engines.