I've been told that most examiners will only mark the first two, regardless of which ones are correct. I've also been told that the odd kindly examiner may mark the two correct ones, regardless of in what order you wrote them.
Curiously enough, you know those english GCSE papers, where you choose to answer question 1 OR question 2, and you have to write an essay? My english teacher told us that examiners will mark both essays, and give you whichever one yields the best marks.