pro apple user since 1991.
One camera is a 28mm F1.8 with OIS and sensor, the other is a 56mm F2.8 normal lens with no OIS and it's own sensor, read, not telephoto that optically doubles ( 2x ) the magnification of the two cameras in use. I am not sure how it is dealt with when in between 1-2X but beyond 2x is "digital zoom" which is essentially cropping the native file of the longest lens. There is no real "telephoto" lens in the iPhone 7+, it is just marketing speak. However, the combination of a 28mm and a 56mm lens is not a weak addition to the already great iPhone camera platform. I plan on using it a lot and making a lot of great images with it when not using my professional gear, for my profession.