Google Webmaster Central Blog has a post on duplicate contents issues and guidance. “Generally, we can differentiate between two major scenarios for issues related to duplicate content:“
- Within-your-domain-duplicate-content, i.e. identical content which (often unintentionally) appears in more than one place on your site
- Cross-domain-duplicate-content, i.e. identical content of your site which appears (again, often unintentionally) on different external sites
With the first scenario, you can take matters into your own hands to avoid Google indexing duplicate content on your site. Check out Adam Lasnik's post Deftly dealing with duplicate content and Vanessa Fox's Duplicate content summit at SMX Advanced, both of which give you some great tips on how to resolve duplicate content issues within your site.
Tip: To help avoid content on your site being crawled as duplicate: include the preferred version of your URLs in your Sitemap file.
To deal with offsite content, as in the second scenario, consider tips like providing slightly alternate versions of your content for syndication, ask your syndication partners to include a link back to your original content. You can find some additional tips on dealing with syndicated content in a recent post by Vanessa Fox, Ranking as the original source for content you syndicate.
If the other site ranks above you, ensure:
- Check if your content is still accessible to Google crawlers.
- You can look in your Sitemap file to see if you made changes for the particular content.
- Check if your site is in line with webmaster guidelines.