In some cases, files are double-extended to hide their true nature (though usually, this involves different extensions like .mp4.exe ). Technical Characteristics of MP4

This numerical string is likely an internal ID or serial number assigned by a specific platform, camera, or automated system (e.g., a security camera or a content management system).

On Windows, right-click the file and select Properties > Details to see metadata like resolution, frame rate, and bit rate.

Open the file using a standard player like VLC Media Player or Windows Media Player .

It is designed to work across almost all modern devices, including smartphones, PCs, and smart TVs.

Having two .mp4 extensions typically happens in one of three ways: