Roller boards, duffel bags, backpacks, purses, and every other bag you can think of is brought on the plane. Per FAA regulations all passengers are allowed 2 carry-on. One is your carry-on bag and the other is a personal item like a purse, laptop case, or briefcase. This is because you are meant to put one bag (the larger bag) in the overhead bin and the other bag (the personal item) under the seat in front of you.
Just because you heard you are allowed 2 carry-on items does not mean that both items go in the overhead. You may put both up there but that’s just a rude move on your part. Space is limited and taking up 2 spaces means someone towards the end of boarding may not be able to bring their carry-on on board.
It also might mean another passenger will have to put their carry-on bag a few rows back and have to wait during deplaning to retrieve their bags. Overhead bin space is shared space so that means you do NOT own the bin above your seat. Be thoughtful of your fellow passengers and keep smaller items under the seat in front of you and be understanding of limited space when you are towards the end of the boarding process.
Don’t be THAT person…