Simple answer: it depends on what I value. If what I value is maximized by there existing two copies, then I should prefer B to A; otherwise not.

For example, for any V I value, it depends on to what degree I value V existing in the world, vs. valuing my experience of V. If I value V in the world, and I act to optimize the world for V, then I should value B over A because the two agents thus created will create more V. Of course, that reasoning applies just as readily to creating agents that aren't simulations of me at all, but nevertheless acts to optimize my environment for V.

For example, for any agent A, it depends on how much I value A-moments, and how much I value distinct A-moments. Again, this has nothing to do with simulations: this is no different from my preferring that some other person live an extra ten years, given that I value that person's agent-moments.

Of course, you already knew all of that.

So I suppose the core of what you're asking is, to what extent should you value a simulation of you having non-unique experiences?

I don't know. Perhaps a simpler question is: how much do you in fact value it?

Speaking personally, I don't seem to value it very much. For example, if you were able to create a simulation of me repeating the last year of my life in a simulation of my environment for the last year, I would not especially care whether you actually did so or not. (I'd be willing to pay to see it done for the novelty/entertainment value, I suppose, and possibly even for the educational value, but those seem to be separate questions.)