I had no idea. I created my account on our laptop that we share and was using my iPhone to run the apps, but I found that I needed to have my phone available so I have begun running them on an old iPhone we had lying around. My DH created his account on our laptop and began using the old iPhone to run the apps. (Funny thing is when he made his account, I didn't even know about referrals, so no need for them to think anyone made two accounts for that reason.) Our accounts have two different email addresses. So you're saying because we created the accounts on the same device, there could be trouble? I never even thought about that.