i would have to agree. a chironomid pupa doesn't hatch out of a chironomid pupa,would make more sense if it was an adult coming out of the bottom one,but even that doesn't make sense because the adult comes out when the pupa is on the surface..either way i am sure it catches fish and that is all that matters.
As one of the tiers in the first link, I can assure you the fly works very well when the chironomids are coming off in swarms. I have been on lakes up here in BC where the buzz of the chironomids sounded like power lines in the winter, they were hatching so thick. It is meant to look like two chironomids rising in very close proximity, not conjoined. The trout seem to see it that way.
Hmmmm, this started the wheels turning (yes, that screech is rust). I just returned from Lake Lenice and spent yesterday afternoon watching cruising, feeding trout turn up their nose at a variety of offerings. [No sympathy required/accepted as I had a good morning overall.] Still, there was a tiny midge hatch, probably 22-26s. I wonder if a double midge tie, with each contributor in the appropriate size, would have made the afternoon. To the vice!!