as to interesting 'two tails' i dont know answer to that, i even visited my old virtual hangout - comet central - comets_ml to see if there was answers there from the many knowledgeable experts, after short search i couldnt find one!? but i suspect? it is something to do with parabolic hood of dust tail seen in early pics
http://www.sott.net/image/image/s4/89554/full/ebr.jpg creating effectively two tails, so material releasing jet(s) are on sun facing side of comet, creating an apparent gap behind .. i read here the tail is pointing towards earth at the moment, from our perspective, ... also in a weird way.. and its only my weird take on it tails also appear to cross over each at some point, not unlike the intersecting meeting points of a venn diagram lol - my expalnation is probably way off, anyway i tried to make sense of it
