Is there an easy way to create a duplicate of a media library image?

In many cases WordPress Thumbnails are fine for displaying a smaller version of an image, however there are quite a number of tools which don’t allow the choice of displaying a thumbnail, so an additional (smaller) copy of the image in the media library seems like the obvious solution.

Duplicating the image then scaling it would achieve that goal without a 3rd party graphics editor.

It is possible to download an image and upload another copy of it, but it’s not a very elegant solution. Is there another way to simply duplicate a media library image, such as a line of custom code to go into functions.php?