It feels wrong. If more people are put into the overcrowded prison, its capacity will raise? IMHO it will be even more over capacity and the capacity is what the place was calculated and designed for. Sure, in a normal bed you can have 2 people sleeping instead of one. Does it make the bed capacity=2? Or benches in the park. You could have a lot more people sitting on a bench, if you accept they sit on each other, still we do not tag the capacity of benches like this. Why should we do it for prisons?