Retaining artifacts after loss

[rgp151]

I've noticed that opponents retain their artifacts after a loss. In Classic MoM the artifacts go to the winner. In a game currently an AI has a godly artifact that they keep putting on a new hero each time I kill one, and its very difficult to kill the heroes, usually requires that I use flying units and hit the hero with direct damage then time out the fight and do it again and maybe even a third time. But I never get the artifact and they keep sending in new heroes with the same artifact.