You know how Knitters like to make things harder than they need to be? Well, hence this question. "Hold Yarn double throughout" does literally mean to use two strands of yarn from two seperate balls, right?
and it doesn't have to be from 2 seperate balls either... I usually pull out the center strand and combine it with the outside strand; since I don't have a fancy yarn-holder-bracelet-thingy like amy does, I jab my left hand through the center of the ball and hang the yarn on my wrist; works very well.