throttle cable question

I just put some GP touring bars on my LTD, and managed to get my existing cables to work, but there is some binding. So I'm going to get me some Z1R cables for it.

My question is, why do some models have dual throttle cables and others have only one?
And since there is already a return spring on the carbs, do I really need the second (push) cable?

Other than that, the bars work fine. Feels like a whole nuther motorcycle.

BTW, that road in my avatar is under water right now.

Sure you can run just the single if you like. Works much better with low bars. You can even gut out the push cable and install it just to look like it's there if you like.

Thanks Ron.
I went ahead and ordered two from Z1E anyway.
Another fellow KZer told me he just runs one, but he has another one not being used running along side it.
That way if/when the first one breaks he can easily switch to the other one.
I like that idea.