Is text considered a page duplicate?

Question

Search Engine Optimization

I have a website - like a public Vkontakte. All posts with all content are displayed on the main page (i.e. the text is published on the main page in full). Posts are small, 500 characters somewhere, on a separate page (single page - I have WordPress CMS), the same post is also published in full and you can read comments from below.
Question: is it considered a duplicate when both the main page and the separate text of the post are published in full. If yes, what measures should be taken? And is it worth it?

Answer 1

It is believed that usually for this, instead of a full post, a short text is published on the main page, something like a description, or they make a post under the cut. In WP, this can be done by inserting the appropriate tag after the introductory text:
Thus, everything after this tag will be visible only on the page with the post.