Step 2.5: Duplicate Content
Basic Concepts | On-Page | Canonicalization
This is a very common term in SEO, the concept of which underpins a lot of (if not all) canonical issues.
We use this term in a specific context, although canonical duplication or configuration issues previously described are duplicate content issues; we differentiate these two categories.
When we talk about duplicate content in this context we mean content that is duplicated but not as a result of poor or incorrect canonical configuration.
This falls into one of two categories:
Internal Website Duplication
Simply put, this is content that is duplicated within a site, this can arise through a number of legitimate activities that aren’t being handled properly with a canonical tag.
External Website Duplication
This where one site duplicates the content from another site and can happen for legitimate or completely illegal or untoward reasons. This is difficult to resolve if your content is duplicated on another site illegitimately, because you cannot add a tag to your site to resolve it.