No, it's a real method that has been employed for decades. You can take two umbrellas, for example, and place then one above the other, on the same light stand even, and shoot right through the space between them, in an over/under setup. It gives very soft light, with minimal shadows, and can give an upper-eye and a lower-eye catchlight, which looks kind of cool. Same with side-by-side, with two umbrellas placed close together, and the camera aiming right through the space between them...same story...a large source of soft, nearly shadowless lighting. Same with softboxes...two,or three can be stacked. For lighting large expanses, I remember a How We Shot It write-up of a Lear jet on the tarmac, that had been lighted by eight, 400 Watt-second umbrellas spaced along the entire length of the aircraft and powered by generators...and the light was very nice and even along the entire length of the plane, which was shot at dusk.
I would wager that just about every odd lashup, jerry-rigged, cluster-f****d combination of lights and modifiers and panels and scrims ever possible has been used, at one time or another...