Files with these naming conventions often circulate in "grey market" archives or personal media servers like Plex. They represent a cultural tug-of-war:

If you find "Pocahontas 1995.mkv.mp4" in your library, it’s likely a relic of a DIY conversion job—a "hand-me-down" file passed through various hard drives. It’s functional, slightly messy, and a perfect example of how 90s nostalgia lives on through fragmented digital bits.

Someone likely took an MKV file (which supports high-quality video and multiple audio tracks) and ran it through a converter to make it a more universally compatible MP4, but forgot to delete the old extension.