Two Door Convenience... The Double Door construction allows more flexibility in placing the crate in your home, or vehicle.
With a Single Door crate, the crate must be placed to allow you to access the end door only.
With an additional door on the side, the Midwest iCrate Double Door can be placed in the corner of a room, say in a location that would cover the end door, but leave the side door available for entry and exit. This is a particular benefit on the larger crates, for people with limited space who will need more options on crate placement, or if you want to place the crate sideways in the back of your vehicle.