David Pitlyuk sent words about a WordPress plugin that will help get you out of Google’s Supplemental index. The Duplicate Content Cure Plugin for WordPress is a very simple, yet effective SEO plugin that prevents search engines from indexing WordPress pages that contain duplicate content, like archives and category pages.
It does this by adding the meta tag on the problem pages. Installation is very simple.
1. Download the plugin
2. Place the file duplicate-content-cure.php in your plugins directory
3. By default, category pages will have the noindex tag added. If you wish to allow your category paes to be indexed, just change the $index_category_pages variable in the duplicate-content-cure.php file. See the example below:
$index_category_pages = false;
$index_category_pages = true;
4. activate it on the plugins page
That’s it. Say goodbye to those pesky duplicate content pages for good.
The plugin won’t replace a good robots.txt file but it’s very easy to use and will eliminate the biggest cause of duplicate content on a WordPress blog.