See how the bottoms of the cookies are darker than the tops? With a single pan, the pan heats up quickly and cooks the bottoms of the cookies faster than the tops (because metal is a better conductor of heat than air). With double-panning, this effect is lessened.
See how the bottoms of the cookies are darker than the tops? With a single pan, the pan heats up quickly and cooks the bottoms of the cookies faster than the tops (because metal is a better conductor of heat than air). With double-panning, this effect is lessened.