Find and delete duplicates posts, pages, custom post type posts and set 301 redirect to the new or old URL.

Get rid of duplicate posts and pages (any post type) on your blog with manual or automatic modes.

Simply prevent duplicate submissions by blocking the submit button while submitting

Deprecated Prevent visitors from leaving duplicate comments/pingbacks/trackbacks to a post.

Deletes duplicate posts from the database (without affecting menus) each time a new post is published.

Prevents duplicate Gravity Forms submissions caused by the same POST request sent more than once.

Find and delete duplicates posts. There are extensions that allow you find posts with similar content, redirect duplicates to the post you are keeping, etc.