To attempt to resolve the ‘Content area not found’ error produced by Elementor, I was advised to insert the string
the_content(); just above
get_footer(); in the single post template (single.php) which is used by WordPress to render a single post. As soon as the line was commented, the problem of duplicating content in the frontend literally disappeared from all 200 posts.
I apologize for the improvisation, but until a few hours ago I did not know how to solve. If it can be useful, to find this problem of mine, the following plugin has helped me a lot: Which Template Am I
Happy CODING everyone!