For understandable reasons, the first generation returned to Touch ID.
Sam Rutherford for Engadget
You might have a hard time trying to get hold of one yourself for the foreseeable future, but the iPhone Duo has been in the hands of reviewers for a little while now. And while it is clearly a first-generation product, overall impressions of Apple's first foldable have been broadly very positive.
One potential annoyance for anyone coming from another modern iPhone, however, is the lack of Face ID, with Apple instead opting to go back to Touch ID for the first time since 2022's iPhone SE. Most iPhone users will have been using Face ID since the iPhone X. In our own review we said the Touch ID solution here works accurately, but can take a bit longer to unlock the phone than you might expect, and according to reliable Apple insider Mark Gurman, the company is already looking at how it can bring its newer technology to the iPhone Duo's inevitable follow-up.
Speaking on his new Power On podcast, Gurman said Apple is "actively working" on under-display Face ID, and that there are already iPhone Duo 2 prototypes that have the technology built into the phone's outer display. He also pointed to the iPhone 18 Pro and Pro Max, with their shrunken down Dynamic Island hardware, as evidence that Apple is finding ways to move more components underneath its phones' displays. The first-gen iPhone Duo also features Apple's first under-display camera.
As for why Apple chose to outfit its $2,000 foldable with a feature it largely retired from iPhones almost a decade ago (although plenty of MacBook and lower-end iPad models still use Touch ID), it likely has a lot to do with the fact the iPhone Duo is designed to be used in a number of different orientations. Putting Face ID sensors on both the inner and outer displays might have been a bit of a stretch, and may have pushed up the price of an already enormously expensive device.
Gurman points out that the iPhone Duo's display is very thin, so squeezing even more components into it would have also been challenging. Apple wanted uniformity with both displays, so getting Face ID into one but not the other was unlikely to materialize this time. The Bloomberg reporter added that the action button, which Apple introduced on the iPhone 15 Pro, may also feature in an eventual iPhone Duo 2.