SEO No Duplicate

This plugin helps you manage your search engine duplicate content, by setting your post page's canonical to the permalink.

Author:Thaya Kareeson (profile at
WordPress version required:2.7
WordPress version tested:3.3.2
Plugin version:0.5.0
Added to WordPress repository:14-02-2009
Last updated:04-06-2012
Warning! This plugin has not been updated in over 2 years. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
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Total downloads:53 048
Active installs:2 000+
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This simple plugin helps you easily tell the search engine bots the preferred version of a page by specifying the canonical properly within your head tag.

Why would you do such a thing? Simply because many black-hat SEO folks abuse duplicate content to gain search ranking and search engine try really hard to detect and penalize them. The last thing you want to do is present yourself as an SEO spammer to search engines.

WordPress 2.9+ includes rel="canonical" header settings by default but the feature only works properly on singular posts (not category or archive pages). So for example:

The second page of your homepage should actually have its canonical URL set to: "" instead of ""

Using this plugin solves the above issue in WordPress 2.9+.