You do see this in the marketplace. As but one example, Shunyata uses copper and silver in their VTX technology in the Omega (and I think other) lines.
Your post is a little ambiguous in that it could be interpreted as using conductors of both materials (as in above example) or an amalgam of both metals as a single conductor, or even a plating of silver over copper.
All of the above are found in the audio world, the effect of which is open for debate. For me, the Omega XC "sounds" great in my system.
An adjacent question I have pondered is when you *mix *high-purity copper with silver or gold, what do you have for conductor purity?
Wouldn't you have a "less pure" conductor? Now, if it sounds better, it sounds better, but I wonder if some manufacturers trade on the *value* of gold and silver as a more expensive/precious metal to make a conductor *metaphorically* more pure/desirable based on cultural attributes and valuations.
