I don't think I would place more value on lock-step copies. I would love to have lots of copies of me, because then we could all do different things, and I'd not have to wonder whether I could have been a good composer, or writer, or what have you. And we'd probably form a commune and buy a mansion and have other fun economies of scale. I have observed that identical twins seem to get a lot of value out of having a twin.

As to the "value" of those copies, this depends on whether I'm speaking of "value" in the social sense, or the personal utility sense. They wouldn't increase my personal hedonistic utility very much, maybe double or triple it; but the increase of utility to the world would probably be more than linear in the number of copies. I would probably make decisions using the expected social utility. I'm not sure why. I think my personal utility function would make me suffer if I didn't.