I did a trial run with the iPhone 8 getting ready for the iPhone X pre-order. I "pretend" ordered 2 iPhone 8 plus'. You have to put each iPhone in your cart separately & when you go to the checkout they will both be there. I'm ordering the SIM Free models & it was very simple to order 2 or more. I know it will be very stressful when October 27th rolls around. It goes really fast (my reason for the iPhone 8 "pretend" pre-order). Also, Apple has a Barclays Visa card that I was told by an Apple employee is their preferred credit card & it will appear in the checkout as payment for your Apple purchases. All the card info will already be there at checkout which will also save you the stress of inputting your credit card numbers. I'm all about getting in & getting out in as little time as possible. I've been ordering iPhones since '08 I learn something new each time.Can't you just add them both to your cart, and then check out?