On Webmaster Central Blog, Google returns to the concept of duplicate content and takes stock of what is considered as such and what is not. We talk a lot, wrongly and through, about the duplicate content penalty when in most cases it is not applied …

The duplicate content penalties revolve around the idea that you shouldn’t have similar content from one site to another. If you copy content from another site and republish it without adding value, Google considers that it does not meet its Guidelines.

So avoid:

  • Create many pages, many sub-domains or many domains with the same content.
  • Sign up for affiliate programs without having a value added approach.

From the moment the duplicate content is made to hijack the results of search engines, there may be a penalty.

However, in general, the rest is not considered duplication of content. For example, if content from your site is presented under two different URLs, no penalty will be imposed on the site. Some CMS can generate this kind of duplicates, it is inconceivable for Google to penalize this. Google will display only one of the two URLs by selecting the one it considers most relevant.

If you’re not happy with the URL Google has chosen, just point it in the sitemap file.

Basically the idea is not to worry about duplicating content. If you have nothing to reproach yourself with, you will have no penalty.

Personally, I have never observed a downgrade or drop in traffic related to duplication of content. The home page of this blog is visible under two URLs, there has never been a problem.

And have you ever observed a negative effect on your natural referencing due to duplication of content?

Source: Webmaster Central Blog.