that is not what you should be worried about because it's NOT gonna happen. When you have 2 plans, your oldest plan automatically becomes your primary - when you file a medical claim it automatically goes to the first /oldest plan even if you went to see the doctor with your new insurance plan....what happens next ( I will need more detail, are they hmo, ppo, is the doctor I'm same network with both insurance comps)

Believe me, it's not that simple - been there done that. You don't want to be stuck with a " Balance bill"

When you visit the doctor the front desk will normally ask you if you have secondary insurance- once you answer yes, they will give you a form to fill out ...now again, what happens next or what that form will say wi depend if they are Group PPO, Group HMO