Will a motel cost more if....?

There are 6 kids in a room? I'm looking at room rates for Motel 6 for a trip that me and my friends might go on in the fall. They say that people under 17 always stay for free, and only charges for adults. But, my mom said that they might charge for having so many people in one room (if you're wondering how we'll sleep, we're bringing sleeping bags, sounds kinda weird, I know...). So, will they charge extra?