One of those pieces is considered a breast half. Each chicken has one breast piece and it is usually cut into two pieces along the breast bone, yielding a breast half, whether boneless or with bone. So if the recipe calls for a breast half, you shouldn't need to cut them. It's not a silly question, but the real question is why does a chicken have only one breast?
Congrats on the 18 lbs!
Life's a journey, not a destination.
It's easier to stay on plan than to get back on plan.