There isn’t anything in ACF that will let you duplicate and existing post including all field on the front end. There isn’t even anything that will do this in the admin. I’d suggest taking a close look at this plugin https://wordpress.org/plugins/duplicate-post/ and asking the developer if there is any way to implement this on the front end of the site.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users