Bernhard Kau

This plugin checks the title of a new post/page or any other post type for uniqueness. The plugin provides a filter <code>unique_title_checker_arguments</code>, which enables you to modify the <code>WP_Query</code> arguments used to find duplicate titles. You may use it to search in more than only current post type for a duplicate title.
This plugin is an enhancement of the <a href="https://wordpress.org/plugins/duplicate-title-checker/" rel="ugc">Duplicate Title Checker</a> by <a href="https://profiles.wordpress.org/ketanajani/" rel="nofollow ugc">ketanajani</a> which only supports posts but not pages or custom post types.

Unique Title Checker

Useful plugin to check duplicate page titles!

A simple plugin that checks the title of any post, page or custom post type to ensure it is unique and does not hurt SEO.

Naksheth Surabhi

A simple plugin that checks the title of any post, page or custom post type to ensure it is unique title, provides alert message for prevent duplicate post title, publish unique post title when adding new post and does not hurt SEO.
This is plugin is an enhancement of the Duplicate Title Checker by ketanajani which only supports posts but not pages or custom post types.

ZPLMOd – Title Checker

A simple plugin that checks the title of any post, page or custom post type to ensure it is unique title, provides alert message for prevent duplicate …

Unique Title Checker vs ZPLMOd – Title Checker