If a game is manually added, then it will indeed be considered a different game than anything else currently in the list. If a game isn't being identified, then there's something different about it that is making it not being picked up. It could be the platform name, could be the title, file name, etc. Games should be picked up after the fact, but the mechanism for picking them up is more restrictive after the fact than for the initial creation of the arcade playlists, if that makes sense.