A file cannot natively be two containers at once.
The group is a known P2P (Peer-to-Peer) release group. While they are prolific, their releases are often scrutinized for the following: doom.patrol.s04e02.1080p.web.h264-glhf.mkv.mp4
Remove the redundant .mkv or .mp4 . Check the actual file properties to see which container it truly is. A file cannot natively be two containers at once
Double extensions are sometimes used to hide malware (e.g., file.mp4.exe ), though in this context, it is likely just a naming glitch. though in this context