他這麽說是把自己當成primary insurance了的，

一旦有兩家insurance, 這兩家就會有個先後，即primary和secondary。在這種情況下，就會有一個coordination of benefit. 第二家如何理賠就要看保險合同的細則了。
推薦一個整形牙醫對此的有關回答：
Q: I have a $1500 benefit, and my husband's plan has a $2000 benefit. My HR rep/insurance agent told me that both plans will pay. Won't they?
A: Maybe, and maybe not. There are a couple of issues here. The first is that most insurance companies do something called "Coordination of Benefits." It sounds very nice, doesn't it? The insurance companies are working together for my benefit... It's the opposite. They found a way to NOT pay your benefit that you thought you had. Here's how it works: The plan with the $1500 benefit is the primary plan (see below), and the one with the $2000 benefit is the secondary plan. All situations with more than one insurance coverage require that we submit to the primary insurance company first, then when we get the explanation of benefits (EOB) from them, we have to submit that, along with another insurance form to the secondary company. In this example, we submit to the first insurance company, and they send back an EOB that says that you are to receive $1500 (as long as you keep your job for the entire length of time that they will be paying the benefit out). We submit that to the secondary company, who says, "Oh, you are getting $1500 from the first insurance company. Well, your benefit with us is a total of $2000 and since you are already getting $1500 from the other company, we only have to pay $500." The "coordination" is seeing if the other company paid anything to you so that they can deduct that amount from what they are supposed to pay. When you have more than one plan, you need to ask both companies if they "coordinate" benefits. On the bright side, some companies pay the entire benefit that they say you have in addition to what the other company pays. You can know this ahead of time if you call both companies and ask how they do this. But you have to specifically tell them that you have two insurance plans, confirm whose is primary, and ask them if they coordinate the benefits with the other insurance company or not. We can then help you figure out what your net benefit is going to be based on which company is primary and which is secondary.
摘自：
www.orthonj.com/practice.html