Alley

Matthew Boynes

WordPress has a wonderful editing model with its “draft workflow”, where writers can save unpublished drafts, preview posts, submit drafts for review from a superior, and even schedule a post’s publication. This is all that most writers and teams ever needed for a blog. WordPress has extended beyond blogs, and has grown to be the preferred platform for any person or team writing for the web. While WordPress has evolved, its editing model has not, and this editing model is limited. Once a post is published, edits cannot follow the same workflow. That’s where this plugin comes in. This plugin has two powerful features, the ability to clone posts and the ability to replace posts with another, which combined, allow writers to leverage core’s “draft workflow” for published posts.
<h4>Features</h4>
<ul>
<li>Create clones of existing posts. The replicas are created as drafts, and have all the same data (including terms and post meta) as the original post. The only things not cloned are child posts (which include revisions, attachments, and other posts)</li>
<li>Replace one post with another. The replaced post becomes a revision of itself, the replacing post is essentially deleted, and you’re left with the replacing post’s data with the post ID and slug of the replaced post.</li>
</ul>
Combined, these features give writers a pseudo-“fork and merge” model. Published posts can be cloned, the clones edited as any other draft can be, then the originals replaced with the clones.
Individually, these features are equally as useful. You don’t need to use the “fork and merge” model to take advantage of this plugin.

Clone & Replace

Gives you the ability to clone posts, and replace posts. Together, you have a very powerful tool for a fork/merge editing model.

Shail Mehta

This Plugin is use for create functionality to duplicate any post / all post types, including taxonomies & custom fields
Primary Features 
* Very easy to create duplicate post or duplicate custom post 
* This plugin is free

sm post duplicator

This Plugin is use for create duplicate post or duplicate custom post

Clone & Replace vs sm post duplicator