Unique Content helps you solve the repetition of blog posts on multiple blocks. This problem actually occurs when you add multiple Post Blocks on a single page without sorting them with any criteria.
Here is an example, I have added three blocks on a single page. And, as I have not sorted them with any criteria, all Post Blocks are displaying the same (latest) blog posts.
So, we have introduced the unique content group feature to solve this issue. As I want to solve the repetition issue of three post blocks, I have to add all of these three blocks to the same group.
Please check out the below video to learn how to add multiple Post Blocks in a unique content group.
Note: You will not face this kind of issue if you sort the blog posts by your desired criteria, like sorting by category, tag, or any other option available on the Query Builder of PostX.