I have my old iPhone and my new one came in. Can I have both backups with full settings and exact mirror of the image running at the same time? Just in case I don't like the new phone size and need to go back to the old phone temporarily to get another size, I'm assuming I can do this? If changes happen different on each phone, which one gets priority in terms of overwriting? I want to verify here for any issues before I try and inadvertently mess up any settings. BTW, my old iPhone 5S has iOS7 while the new one comes with iOS8.