This one from the official DVD looks like the blades are intertwined.
Also, I think some are getting "behind" confused. Some are thinking of it in relation to the picture: Vader's sword is behind Luke's in the picture (Luke's is closest to us). Other's are thinking in relation to the events depicted in the pic: Vader's sword is in front of Luke's and he is blocking it from hitting the Emperor (Vader's is closest to the Emperor).
We're all on the same page, just some of us are thinking objectively and others subjectively what "behind" means.