What is the Meta Keywords Tag?
The meta keywords tag is a piece of code placed in the head element of an HTML document of a page that allows you to list the keywords you'd like to target.
A typical meta keywords tag:
A long time ago when the internet and SEO were just in their beginning, this tag factored heavily into ranking decisions for search engines. Today, most search engines such as Google do not use the meta keywords tag as a ranking factor, though there are some search engines that still use them.
What Does "Duplicate Meta Keywords" Mean?
URLs with this issue have the same value for their meta keywords tag as one or more other URLs.
Why It's Important
If you're targeting a search engine like Google, Bing, or Yahoo, you don't need to do anything – these search engines ignore this tag. However, if you're targeting a search engine that uses meta keywords in their ranking algorithm (like Baidu), it may be a good idea to include it on each page you want to be reached via organic traffic.
Since it's not a good idea to optimize for the same keywords on multiple pages, each URL's meta keywords tag should be unique. If you are trying to target the same keyword on multiple pages, search engines may get confused as to which page is the most relevant to rank for this keyword. When this happens, it's almost like you're competing with other pages on your site.
Having duplicate meta keywords tags means that you are targeting the same keyword on multiple pages, which is why it should be avoided.
How To Fix
Write a unique meta keywords tag for this URL using the page’s targeted keywords. You should do the same for other URLs on the site with this same meta keywords tag too. Follow these guidelines for best practices:
Guidelines for Writing an Effective Meta Keywords Tag
Only include the top 3-4 keywords you're targeting on the page. (Best practices are to not target more than 3 keywords per URL anyway).
List each keyword (or keyword phrase) descending by importance, comma-separated.
The meta keywords tag should be no more than 100 characters long.
Avoid keyword stuffing and duplicating the same keyword.
Each meta keywords tag should be unique. No URLs should have the same meta keywords value.