Great example. Some private trackers have strict rules about quality, e.g. at most one 720p and at most one 1080p (probably 1080p and 4k nowadays), bitrate must be above a certain threshold, whichever was published first stays, unless there is an "official" version published by the same people maintaining the website. The exact opposite of decentralized torrent sites, and works really well. Takes a lot of work, obviously.