One of the many issues that the Site Auditor checks for is duplicate page content. If a group of URLs are included in the Duplicate Page Content report, this means that the content found on each URL is either exactly the same or very close to the same.
Occasionally, there may be a set of URLs included in this report that look very different when you open them in a web browser. There are a few likely reasons why this may be:
Potential reason 2: The URLs may be different
Search engines may have a different interpretation of what duplicate content is than you do. Search engines expect every URL to contain unique content.
For example, while you may think of these as all the same page, they are all unique pages to a search engine:
Therefore, if they all have the same content and are not using rel=canonical correctly, to a search engine and Dragon Metrics' Site Auditor, they are duplicate content.