I always try not to ask for the extra paper in exams because I really think that examiners just wont look at it. They are marking our papers so quickly will they really be bothered to look at the extra sheets, especially if we did OK in the question.....
All exam papers get scanned onto a computer as a load, and the examiners mark it from there. So I'm guessing since you put all the paper in the same pile, the whole lot will be scanned, and the examiners mark everything from there...