Yoast has posted an interesting article “Duplicate content: causes and solutions” The article describes how to use Google Webmaster Tools to identify duplicate content.
The in-depth article covers:
Causes for duplicate content
Misunderstanding the concept of a URL
Session ID’s
URL parameters used for tracking and sorting
Scrapers & content syndication
Order of parameters
Comment Pagination
Printer friendly pages
WWW vs. non-WWW
Conceptual Solution: A “canonical” URL
Identifying Duplicate Contents issues
Google Webmaster Tools
Searching for titles or snippets
Practical Solutions for Duplicate Content
Avoiding Duplicate Content
301 Redirecting Duplicate Content
Using rel=”canonical” links
Linking back to the original content
Conclusion: Duplicate content is fixable, and should be fixed
Well worth reading for WordPress and non WordPress site operators.
Full article: http://yoast.com/articles/duplicate-content/
