Backpack As Goodie Bags Does A Rolling Backpack Count As A Carry On Baggage?

Does a rolling backpack count as a carry on baggage? - backpack as goodie bags

I am planning to fly to Asia for the summer. And for the first time flying alone. I fly Northwest and allow hand luggage and a backpack.

My question is: Can I wear a backpack with a normal backpack slipped my hand luggage?