Here’s a situation that will affect on a small number of people. I have an iPhone and an iPod touch. I use the iPod touch as, essentially, a tiny internet tablet in my home. The idea is that I won’t drain down my iPhone battery at home by using the iPod  touch instead. Generally speaking, this works great for me. Here’s a caveat for this use case if you use the new Starbucks Card Mobile to track the balance on Starbucks Cards: You can store and use a Starbucks Card number on a single device. The app gives the message above and wipes the number from the device if you have it on two devices. In my case, I installed it on my iPhone first and iPod touch second. I received the  message above while standing in a Starbucks store waiting to order a beverage. The last device installed (the iPod touch in my case) gets precedence. So, the card info was wiped from my iPhone. The lesson leanred is to install and use the Starbucks card app on only one device (which is probably the case for the vast majority of iPhone users).