Kishores

This is a WordPress plugin which helps in adding 
an option to your posts to enable display of more than one author-name on a post on WordPress.
<a href="http://opentuteplus.com/wordpress-post-contributors/" rel="nofollow ugc">Demo:</a>
TODO : Ajax filter for showing author on dashboard.
<h3>Arbitrary section</h3>

WordPress Post Contributors

Add an option to your posts to enable display of more than one author-name on a post on WordPress.

sujitkumar87

WP Post Contributors plugin allows you to add more than one author to the post who have contributed. 
The contributors meta will apear just aside of your post body. Just check the authors who have contibuted. 
And update the post to save it.
Features of Custom News Widget:
<ul>
<li>User friendly and easy to use.</li>
<li>Tested with other popular plugins.</li>
<li>Add authors to the post easily.</li>
</ul>

WP Post Contributor

WP Post Contributors plugin allows you to add more than one author to the post who have contributed.

WordPress Post Contributors vs WP Post Contributor