I had my sailmaker (Leading Edge) make a jib identical to one I had, with the hanks staggered. He did such a good job that even the luff tensions are identical when the twins are hoisted. I've only once seen that accomplished with a roller furler: the owner had two light jibs that would roll up together, so when fully unfurled you had the equivalent of twin jibs. It was 30 years ago, and my memory is foggy on how he did that.
The small air gap between the luff edges at the forestay seems to improve stability, much like the apex vent in a parachute reduces oscillation. The temptation is to seal it somehow, but I believe it's beneficial and has little effect on efficiency. At any rate, I was surfing along well above hull speed, my hand off the tiller, with the boat not rolling and standing straight up, so I can't complain.