One SEO professional was concerned about duplicate content coming from combining existing blog posts and asked John Mueller about the following scenario during a hangout:
They were describing a situation where they posted a topic to their blog. However due to some potential need, perhaps they need to post the content to their blog again, with some additional updates.
But, they also want to keep the previous post the same.
Instead, they want to publish the combination of the old post with the new additions.
Their main question is: will this cause their blog to be penalized by re-publishing the same content?
John answered that no, this is usually fine. Google’s systems will recognize when there is significant duplication of content across a website.
However, these are things that are normal activities for a website. So, if you have a category page and a detail page for posts, then on the category page, you’ll have some part of the blog posts as well, which is duplication.
That’s still okay.
This happens at approximately the 7:36 mark in the video.