When adding a video or audio resource to any activity/resource via the 'Insert or edit an audio/visual file' ATTO function, if you delete or wholly replace the title of the uploaded content during playback of this content, it duplicates the content — one with the original title and the other without a title — and said duplication holds upon final save. 

This has been replicated on the 3.11.4 https://sandbox.moodledemo.net/ site, a 3.11.2 and 3.11.3 instance. Demo site replication viewable via this screen recording

STEPS TO REPLICATE: 

1. Login to any 3.11.2 - 3.11.4 site and enter a course with a role containing requisite editing permissions (i.e Editing Teacher or higher) 
2. Click on 'Add an activity or resource'
3. Pick a Label, Page, Assignment etc. activity/resource (doesn't matter which so long as ATTO can be used to edit any field in the initial configuration)
4. Using any description/content field the ATTO editor is available for, click 'Insert or edit an audio/visual file'
5. Click the 'Video' or 'Audio' tab, upload  video/audio of your choice (way to upload does not matter)
6. In the Insert Media popup, under 'Display Options', enter any title in the 'Enter Title' field
7. Click 'Insert Media'
8. Play the inserted video (ensuring the 'Insert an audio/video file' is indented/greyed out)¹
9. While the video is playing, click on the Insert an audio/video file' button 
10. Delete the title or highlight and replace it fully²
11. Observe the video/audio is now duplicated
12. Using the HTML editor, observe the duplication and observe that the first file has the original title and the second is either –- if deleted -- without a title or -- if replaced -- has the amended title 
13. Scroll to the bottom of whatever you were editing and save
14. Observe the duplication has held and saved two copies of the inserted media

Observed: The video/audio duplicates, holds upon save and one copy has the old title and the other a blank title.

Expected: Video/audio title should only be updated, not duplicated

¹: The video must be playing when attempting to follow these steps otherwise this issue cannot be replicated

²: In Step 10, what is meant by replace is highlight, remove, replace as opposed to changing the title without removing all of it (i.e if I called the file 'TEST' to begin with, but modified per the steps that title to "TEST1234" without removing the TEST portion of that title, it will not duplicate the content)