Why does Kimber use two wires for ground

Looking at some of their interconnects it appears that they use three strands ... two for ground and one for the center/positive.

Why would you need two wires for ground??
Normally an RCA connector has a central wire (positive) and a shield (Ground).

An RCA shield most often consists of either a foil wrap or many wires braided together.

In the case you are referring to, I suspect that the braiding of three wires together forms a sort of shield by having two ground wires braided and shielding the positive wire.

Twisted wires work well when you don't have a shield because EM signals emitted from the wires themselves tend to cancel out (less cross talk). However, they are less robust with respect to noise pick up from other sources.

Generally the cheapest wiring is two insulated wires run parallel side by side, then a twisted pair, a foil shielded cable is next, a high density braided shield cable is even more and finally a fairly rigid and precisely manufactured coaxial cable is generally the most expensive.

Foil tends to pose reliable contact problems with connectors at each end but is a better shield than braids. Generally, for audio frequency signals a twisted pair is more than good enough but most people will own braided shielded cables for analog interconnects.