Hello,
I had the same problem.
With Learndash in focus mose and WpDiscuz comments I had two comments sections (the same) in lessons and topics footer.

I resolved with this code:

add_filter('learndash-focus-content-content-after', 'ld_wpdiscuz_comments_enable');
function ld_wpdiscuz_comments_enable(){
comments_template();
};

and adding this CSS (not in WpDiscuz --> Settings --> Styles and Colors --> Custom CSS Code) in general custumizing appareance:

.learndash-wrapper .ld-focus-comments {
margin: 2em 0;
visibility: hidden;
}

Hope this could help someone....
sure, schould be better that code doesn't double comments 😀

Marco