A glimpse inside a filmmaker’s idea lab is not necessarily the same thing as a film, which puts Riley Stearns’ low-key future satire “Dual” in a frustrating position when there’s so much going for it ...

It’s just about impossible to discuss sketch comedy without bringing in Monty Python. Everyone from The Simpsons’ Matt Groening to Tina Fey to Jim Carrey has cited the comedy troupe as an influence.