If I drop my back pack onto the ground i am able to put a backpack inside it and a backpack inside that one. which gives me mores spaces so you should be able to have as many spots as you want. until you become to heavy. Also I somehow glitched to where all my stuff dissapered when i put I droped a backpack out of my backpack then tried to put it into the one on the ground.
You probly shouldnt be able to put a backpack into a backpack anyways since they are the same size lol.