It's easier to rotate the grating. That's how we did this in labs in undergraduate (we did a session on imaging the sun with a high res spectrometer). Or put it on a stepper or servo motor and sweep it in several positions. We used an SBIG camera and a micrometer-adjustable spectrometer. It seems like SBIG got bought up by the folks that make MaximDL. They used to sell these instruments off the shelf for $$$$.

It's more complicated to use multiple cameras on one grating because you'd need far more light shielding.