They is usually what people do when they put a game up for torrents without the renaming of files, those uploaders aren't trying to make money though so this is much worse imo. Some people really scummy.Well the fact that someone is taking the GOG version of the game (which has no DRM) and just repackaging them into a different installer and then selling it is considered piracy, it's not even up for debate....
There are no keys to be deactivated, GOG games have no DRM, the seller probably buys the game on GOG, get's the files and then just repackages them....