Credit: Brothers of the Head: Nick Wall

A glumly serious British mock rock doc: You could forgive the paucity of jokes if Brothers of the Head had anything to say, or if the ’70s-vérité surface were remotely convincing. We’re meant to be wowed by the fact that the heroes are conjoined twins, but as played by Harry and Luke Treadaway — identical-twin pretty boys in mascara — these two self-styled rock freaks don’t add up to one interesting personality. Almost every scene unfolds in the same blah rehearsal studio, where the two bicker, cuddle, and forge abrasively monotonous power-punk ”anthems.”