yeah....i had the thought about you maybe ovulating more than once..but then i thought the same, that doesnt explain the continued dark lines....
i remember my doctor saying that once you get to my age you can ovulate more than once and at any time of the month....but you're only a young un! at the moment i think i just ovulate once...well, i only ever get one surge and the line are only there for 2 days, 3 days max! x