Nobody invents an entirely new presentation format for no good reason. But without knowing a bit more about the Iwerks Quatro system, it would seem that little good reason was used. I'm sure my thinking will be corrected shortly. Back to the subject at hand, the Iwerks Quatro system employs a 70mm print that has side-by-side frames from 35mm four perf film. Despite the images being only four perforations high, the film is advanced the standard 70mm five perfs. The purpose of this system is to provide an extended running time without the use of a platter system. The film is run normally with the aperture and lens showing only one of the images. When the film reaches the end, the aperture and lens shift to show the other frame and the film runs backwards until it gets to the start where the process can be repeated. This system is used only in special venues, obviously. Digital sound can be provided in the form of CD, laser disc, or other format through the use of an interlock.
It's a bit mystifying why a format would be developed that required such substantial modification to the projector and yet the frame height was not reduced to four perfs. Anyone having detailed information on this is encouraged to contact me.