I agree every berthing space has more than one exit. I still don’t get this.
That is not the case. I served on an aircraft carrier and slept in a compartment that had two hatches. One was a deck hatch overhead with a ladder going up to the next deck. The other was a bulkhead hatch that was access to a storage compartment that didn't have any other access.
The more hatches you put on a ship, the more difficult it is to maintain watertight integrity.