I tend to think that exact duplication doesn’t double utility.
I agree.
I guess I think the billions may be the better world if that’s how the total utilitarian math works out.
You don’t have to resign yourself to merely following the math. Total utilitarianism is built on some intuitive ideas. If you don’t like the billions of barely worth living lives, that’s also an intuition. The repugnant conclusion shows some tension between these intuitions, that’s all—you have to decide how to resolve the tension (and it you think that exact duplication doesn’t double utility, you’ve already violated total utilitarian intuitions). “The math” doesn’t dictate how you’ll resolve this—only your choices do.
I agree.
You don’t have to resign yourself to merely following the math. Total utilitarianism is built on some intuitive ideas. If you don’t like the billions of barely worth living lives, that’s also an intuition. The repugnant conclusion shows some tension between these intuitions, that’s all—you have to decide how to resolve the tension (and it you think that exact duplication doesn’t double utility, you’ve already violated total utilitarian intuitions). “The math” doesn’t dictate how you’ll resolve this—only your choices do.
What I meant is that if the utilitarian math favors the billions, that seems intuitively reasonable enough that I have no difficulty accepting it.
That’s fine—you’ve made your population ethics compatible with your intuitions, which is perfectly ok.