The iPhone Duo comes out tomorrow but, given the strong pre-order demand, it is already looking to be a smash hit. And we are all expecting Apple to follow up with a second-generation model next fall, which means the company has to be already working on the next-gen hardware.

On his Power On podcast , Mark Gurman reports that iPhone Duo 2 prototypes inside Apple include Face ID, with the Face ID sensor being integrated beneath the display on the outer screen.

The shift from Face ID to Touch ID on this phone was one of the biggest complaints raised by early iPhone Duo reviewers. 9to5Mac’s Chance Miller called it “the hardest thing to get used to” with the new foldable.

For the first-gen iPhone Duo, fitting Face ID inside the super-thin enclosure seemed to be the blocker.…