I'm pretty sure you'll be ok. But, I have seen supervisors ask them to be checked. As long as its lightweight, I think you'll be fine. TSA has no rules as to how many pieces of carry on you can have. If the airline lets you through with 10, as long as there are no prohibited items, you can have 10. the rules for luggage are airline rules. You can always call the airline at your airport, they are usually pretty knowedgeable about what the TSA allows at their particular airport.