AFAIK, this isn't possible. I can't even think of how it would be done (from a technical standpoint). There is no guarantee that the other half of what you selected has the exact same surface topology, so you may not get the right selection.

Also, are you refering to poly shapes or NURBS? This is the poly/subd forum but you're talking about CVs which are NURBS components. Selection options work differently depending on the type of surface you have.