A duplicate content issue will be noted any time content on a page is the same, or “appreciably similar” to content found on another URL. This is a problem for SEO because search engines don’t know which content source is the original, or most reliable. When duplicate content is found on multiple pages on the same website, Google generally resolves this dilemma by splitting the page views between all of the pages with the same content, reducing the views to all the pages.
To fix these issues:
Find the pages with duplicate content and open them in your browser.
When duplicate content is noted by Moz, it will be noted with a number in the Duplicate Content column. Pages with matching numbers are identified as showing the same content.
Read the pages to find the duplicate content.
Decide which page should contain the content as is. This should be the page that is most important to the mission of your website, or the one higher up in the hierarchy.
Rewrite or remove the content from the page that you chose as the one to change.
Tips to Keep in Mind
The amount of time this will take will depend on the type and amount of content that has been duplicated.
Duplicate pages don’t just come in pairs, there can be three or more pages with the same content, so make sure to look at all of the pages with matching numbers in the Duplicate content column.
It is tempting to cut and paste descriptions for commonly used features or elements on a website, so remember to check all of your descriptions and captions when looking for duplicate content.