I just finished my own plugin to deal with duplicate content in wordpress. I will be honest and admit that after all my reading over the past couple of days, I am unclear as to exactly how duplicate content is identified. However, I believe it is a safe bet to assume that the more similar the content that 2 individual urls contain, the less likely a search engine will like it.

I am heading towards the belief that just having post content in a category page (for example) is not enough by itself to be seen as duplicate content, as long as there are other related posts on that page also. This “dilutes” the duplicate content issue, whilst still allowing you the potential benefit of richer keyword density on a category or tag page. Therefore, I replicated this approach in a Wordpress plugin!

The plugin does the bread and butter stuff, such as stopping the indexing of archives and search results, as well as (optionally) paged content. But what it also does is put the noindex,follow meta tag on all category / tag pages that contain fewer posts than the minimum threshold (default set at 5 posts). The final option is to only allow indexing of parent categories, as sometimes the child categories may look very similar to their parents.

Update: now includes unique meta descriptions, and page title re-writing!

If you have read my other 2 posts [1] [2] so far on duplicate content, you will realise that whilst this approach may have some benefit, it is not possible to say whether it definitely will. However, it is better to be safe than sorry!

PS. You can effectively turn off category / tag page indexing by setting the minimum threshold to above you posts per page limit. I have also included the is_tag() function, which will only work on installations that use tagging, such as Wordpress 2.2+, or use of the UTW plugin. Older versions of Wordpress will just ignore this function.

Download: click here (v1.3)

Installation:

- download the zip file, and open up the plugin file to configure the settings
- if you don’t want to configure anything, default settings will should work fine
- upload the plugin to your wordpress “wp-content/plugins” directory
- activate the plugin from the “Plugins” section of the admin area

If you want to take advantage of the page title re-writing in v1.2, you will need to open up your theme files, and replace the line that begins <title> with <title><?php df_title() ?></title> to activate. You can view the results of the plugin by looking at the meta tags in the source code of various pages on this blog. If you have any questions or comments, please leave some feedback below!

History:

v1.0 - initial release, using meta indexing tags only
v1.1 - added unique meta description tags for all indexed pages
v1.2 - basic re-writing of page titles, using df_title()
v1.3- now supports Wordpress 2.3+ also