What

When users upload MP3 files with images attached, the image is uploaded twice.
This inadvertently adds two images to the Media library. The image and the mp3 file are saved separately, and the MP3 attached image is set as the featured image on the attachment page.

@NoHopeRadio recorded her screen to show how this looks:

Why

This was brought to our attention by a user with Cerebral Palsy.
The issue is that, they would upload, add the alt text to one of the images, and then manually have to go through the media library to find the duplicate with the alt text.

For someone with Cerebral Palsy, this is strenuous physical work that could be avoided.

How

By either uploading only one image file, or none.