Duplicate content can confuse Google. If your content is on multiple pages on your website or other sites, Google won't know which one to rank first. Avoid duplicate content as much as possible. Perform a duplicate content check from time to time to find copied content.
In theAdvanced > RSS section of the Yoast SEO plugin, a snippet has been predefined to add to your posts “This article first appeared on yourwebsite.com”. This link makes sure to include the link to the original article. Of course, this helps prevent duplicate content, as Google will find this backlink to your website.
However, if you write awesome content, your content will be duplicated. And that copy won't always include a link to your website. All the more reason to do a duplicate content check regularly. In this article, I'm going to show you a quick way to find duplicate content for your website.
Copyscape – Duplicate Content Checker
There are a lot of tools to find duplicate content. One of the probably best-known duplicate content checkers is CopyScape.com. This tool works very easily: insert a link and copyscape will tell you where the duplicate content is:
That is the first step. Results will be displayed (9 in this case), presented as Google search results pages. Just click on one for more details.
In this case, the 2% of the Creativ Form page is a copy of the YOAST page. Copyscape highlights text that is duplicated. By doing so, this duplicate content checker will give an idea of the severity of the copy. If it's only 2% of the page like in this case, I wouldn't worry. If it is more than 40%, which is a pretty big part you should simply send a message to ask to change the copied text.
By the way, it is common to find duplicate manufacturer descriptions in online stores. These are usually automatically imported into the store's content management system. Usually not just for your website. Be aware of it. I understand that it is quite annoying to write unique descriptions for each product, but at least you can start with your best-selling products and go from there.
Use the copyscape checker to find content copied from your website or other websites. It is one of the many tools available but this one is free and easy to use. If you want to dive a little deeper into your duplicate content, copyscape also offers a paid version for more information.
Siteliner Internal Duplicate Content Checker
Siteliner is the brother of CopyScapes and search for internal duplicate content. This checker will find duplicate content on your own site. A very common example of this is when a WordPress blog does not use excerpts but instead displays the entire blog post on the main blog page. That simply means that the blog post is available on at least two pages: the main page and the post itself. And probably on the general category pages and upcoming tags. This makes four versions of the same article on your own website.
The advantage of using excerpts is that the excerpt always has an appropriate link to the post. This link tells Google that the original content is not in that blog/page/tag category but in the post itself. I think it is recommended to use half excerpts on all WordPress sites.
Siteliner will show a lot of things, but is limited to 250 pages and 30 days. Again, there is a paid version, but the free one will give you a good idea. Just do a search, view the overview page and click for more details. Don't be scared by a high number of internal duplicate content, as this checker detects even excerpts as duplicate content
Percentages
Google understands what a sidebar is, but copyscape and Siteliner seem to include all text on a page in their percentage calculations. Please keep this in mind when using these duplicate content checkers. The actual percentage of duplicate content, when you only look at the main content of a page, could be higher.
Should I be worried? No. Just click on one of the links and see if this is true.
Manual Duplicate Content Check
Copyscape and Siteliner are nice, easy-to-use tools. However, if you want to see what is duplicated according to Google, you could use Google itself.
If you have a page you want to check, just go to that page. Copy a fragment of text, preferably from a section that you think might be attractive for others to copy. Insert the exact snippet into Google using double quotes like this:
“WordPress is one of the best, if not the best content management systems when it comes to SEO. That said, spending time on your SEO might seem like a waste.” Limit that phrase to 32 words, as Google will only take the first 32 words into account. This search returns 'about 517 results' according to Google, which is well above the 9 results returned by copyscape.
Check your own duplicate content
Use a duplicate content checker like Copyscape to find what has been copied from your site, and use Google to see where else on the Internet this content has ended up. These are simple tools that serve one goal: avoid duplicate content.
Source: Yoast Blog