From now on players can find the same true artifact only once – you ID an artifact by moving on it or picking it up, then you cannot find it again.
Info for new players: there are two types of artifacts – true artifacts and random artifacts (randarts). True artifacts are unique items, which could be possessed by one player at once; when it found by someone, others can’t find it before it would be lost again. Randards is a powerful RNG items; which are not unique and that’s why they could be stored in player’s house (true arts can’t).
Note from PowerWyrm: sometimes you can still find an artifact again – if another player generates the level and hasn’t find the artifact, it can appear and if you recall on the same level, you can find the art before the other player.