I have figured it out the single 'L' is for long nipple, the 'LL' is for Long nipple AND long stem from thread to hex nut. As these are fairly thin walled that may increase possibility of shearing it with a knock and if it gets a little seized or over tightened.
I read a a great review that said YOU MUST spray a little WD40 in the nipple after use and MUST recap with the rubber cap. Otherwise they quickly corrode inside due to the hygroscopic effect of brake fluid. Once jammed or seized they may still turn a quarter thread but nothing will emerge when brake pumped. If corrosion is bad they will seize in threads and due to thin walls will easily shear, same with over tightening without any corrosion. Then it is Easy Out time.