The first is a list of registered AppleCare agreements; the second is a list of registered hardware products. Do you have a registered AppleCare agreement for only one of the phones? If you bought AppleCare for both, are you certain that you registered both AppleCare agreements after buying them?
My understanding is that if you buy AppleCare coverage for a product at the same time you buy the product, and the purchase is made at an Apple retail store or the Apple online store, then the product and the agreement are automatically registered. But if you buy AppleCare separately from the device it's to cover, you need to register the AppleCare plan yourself. And if you buy either or both from a third-party vendor (a reseller), then nothing is auto-registered. If anyone knows I'm incorrect about any of this, please correct me.