The markers will read everything thats written, whether its crossed out, written on ruled pages, or unrulsed pages, whether its under the heading"DO NOT MARK" - in short, they read EVERYTHING adn will give you marks accordingly
In addition dont fret if you wrote two questions in teh same booklet. Either they will pick it up at teh examniation centre and rip out the required pages and staple it into a new booklet, or, if it gets to teh markers, then the markers are instructed to send it back to the head marking centre where a so-called "super marker" is responsible for marking these paticular cases. At no stage will you ever get zero for these things.