What's better, one conductor or two conductors for an RCA interconnect?

All cables have two conductors!

RCA cables are coaxial cables, meaning that each cable has a positive conductor (inner) and a negative conductor (outer).

RCA cables are coaxial cables

Not all, Kimber makes a braided construction cable, for example.

more is better

always

To clarify, I understand that there is one conductor, generally copper, and a shield which I guess also is considered a conductor. And then there are cables with 2 conductors, each a separate strand separately shielded. And then a third wire of sorts that acts as a drain or a ground.

Is it better to have two separately shielded wires, which I guess can have multiple strands twisted around each other, versus a Single separately shielded copper wire?
 

Higher extremely expensive analog interconnects have two conductors Plus a separate wire serving as a ground.  If it don't matter for rca Cable purposes, ie. Unbalanced, why is it done. Presumably because it increases quality, and if so, why?