Luggage/departure on b2b?

I am considering a b2b for the first time, where I would end up having two different staterooms between the two cruises.

What happens when the first cruise ends? Will I be allowed to leave my luggage outside the next stateroom, or somewhere else onboard, and stay on the ship? Or do I need to get off, wait at the terminal and do a new check in?

I would possibly have the dbp on the first leg, with the opportunity to save a few beers/seltzers/sodas in my luggage for the next leg.. would anyone check my luggage if it stays onboard, or is this a valid way of saving a few bucks on the next cruise?