We have a contractor putting in a whirlpool tub that requires 2 15 amp circuits into a GFI plug. The contractor told me to buy a tandem breaker because I only have room for one more breaker. I have a GE box which requires GE breakers. Lowes and Home Depot don't have them but the guy that works there says I can use another brand because it has the same footprint. Is this true?