The ".mp4.mp4" suffix typically occurs when a user manually renames a file or when a conversion tool adds a second extension to a file that already had one.
This format is highly versatile and playable on virtually any modern device, including Android smartphones , iPhones, and Windows/Mac computers. Possible Contents 8684224.mp4.mp4
If you have this file and are unable to open it, follow these steps: A Quick Dive Into MP4 - DEV Community including Android smartphones