William P. Davis

This plugin allows you to duplicate images you have in the media library and attach them to a new post, rather than having to create a new copy of the image and upload it to WordPress again.
It works by copying the post and its metadata. It does not actually copy the image. Any changes you make to the new copy of the attachment — updating the caption or cropping, for example, will only be applied to the new attachment, not to the original.
This is useful if you query posts for its attachments to display photos, or if you make use of galleries and have old images you might want to include, among other things.
To use, go to the Library tab in a post. You should see an ‘Attach’ link.

BDN Duplicate Images

Allows you to duplicate images in the media library and attach them to the current post.

pepe

Scott Bressler

Feel free to get in touch with us about anything you’d like me to add to this plugin or any feedback. We love hearing from our users! <a href="https://wordpress.org/support/plugin/media-credit/#postform" rel="ugc">Start a thread on the plugin forum</a> and we’ll get back to you shortly!
This plugin adds a “Credit” field when uploading media to posts and displays it under the images on your blog to properly credit the artist.
When adding media through the Media Uploader tool or editing media already in the Media Library, this plugin adds a new field to the media form that allows users to assign credit for given media to a user of your blog (assisted with autocomplete) or to any freeform text (e.g. courtesy photos, etc.).
When this media is then inserted into a post, a new shortcode, <code>[media-credit]</code>, surrounds the media, inside of any caption, with the provided media credit information. Media credit inside this shortcode is then displayed on your blog under your media with the class <code>.media-credit</code>, which has some default styling but which you can customize to your heart’s content.
You can also display all the media by an author on the author’s page. See more in the <a href="https://wordpress.org/plugins/media-credit/faq/" rel="ugc">FAQ</a>. 
Options
This plugin provides a few options which appear on the Media page under Settings. These options are:
<ul>
<li>Separator</li>
<li>Organization</li>
<li>Display credits after post</li>
</ul>
Example
This is best explained with an example. With a separator of ” | ” and an organization of The Daily Times, media inserted will be followed with a credit line appearing as follows, with the username linking to the author page for that user:
<a href="" rel="nofollow ugc">John Smith</a> | The Daily Times
Further explanation
Separator: These are the characters that separate the display name for a user on your blog from the name of the organization, as described below. The default separator is ” | ” but feel free to change this to suit your needs.
Organization: This is what appears after the separator as listed above. The default organization is the name of your blog.
Display credits after post: With this option enabled, media credit shortcodes will not appear by default when inserting media into your posts. Instead, the plugin will look through the content of your posts for any media attachments and display something like the following at the end of each post with the CSS class .media-credit-end:
Images courtesy of <a href="" rel="nofollow ugc">John Smith</a> | The Daily Times, Michael Scott and Jane Doe.
In this example, John Smith is a user of your blog, while the latter two credits are not.

Media Credit

Does exactly what is asked of it, resources for developers, what more could you ask for?

Thanks to this plugin

Adds a "Credit" field when uploading media to posts and displays it under the images on your blog to properly credit the artist.

BDN Duplicate Images vs Media Credit