The thing is with a double bladed lightsaber you have a physiological advantage because of the second blade because most people watch it and the primary blade. but in the words of Dark lord Kas'im weapons master of the sith acadamy in the times of darth Bane "The secret to a double sided lightsaber is that where ever the first blade is the other blade is on the exact opposite side. So if you know were one blade is you know were the other blade is"