copyActor() is not intended to be called directly, but you can use newActor = Actor(oldActor) as a copy constructor.
Still, I don’t think the results of using the copy constructor will be very different from recreating a new Actor from scratch each time. In either case, the copy will start from the beginning each time you play, as it should. I’m not sure what you want to happen–do you want the copy to start from the same frame that the original is currently playing, instead of from the beginning? You could do that with an explicit frame number on the play() call, but then your two animations will be precisely in sync, exactly the problem you have when you use instancing.
David