TIEro

This plugin is now available as part of <a href="https://wordpress.org/plugins/tietools-automatic-maintenance-kit/" title="TIEtools" rel="ugc">TIEtools</a>, which also includes post expiry and server log file removal.
A simple duplicate post deletion plugin. Spots posts with the same title and removes all but one of each.
<ul>
<li>Checks in published, draft, pending and private posts on demand</li>
<li>Includes or excludes user-defined list of categories</li>
<li>Moves all duplicate posts to the Trash (leaving the oldest or newest original copy)</li>
<li>Permanent post deletion is handled by WP’s built-in Trash removal</li>
<li>Power button to switch everything on and off without messing with the plugins page</li>
</ul>

TIEdupedeleter Simple Duplicate Post Deleter

Simple duplicate post deleter. Trashes duplicate posts based on status and category. Keeps newest or oldest original copy.

Volt Blocks

A lightweight WordPress plugin that automatically expires posts by moving them to draft status based on expiry date/time.

Post Expiry Scheduler

Automatically expire posts by moving them to draft status based on expiry date/time.

TIEdupedeleter Simple Duplicate Post Deleter vs Post Expiry Scheduler