iPhone Duo 2 Leak Teases Under-Display Face ID for 2027

The iPhone Duo 2 has surfaced in early internal testing ahead of an expected 2027 launch, with Apple working to bring back under-display Face ID as its headline upgrade. Designed for power users seeking seamless biometric authentication on a foldable, the device addresses early hardware compromises—though buyers must currently navigate the first-generation model's steep 15,999 yuan starting price and lack of a dedicated telephoto camera.

While initial buyers are still unboxing the first-generation foldable and waitlists stretch into late January, Bloomberg's Mark Gurman revealed in the Power On podcast that Apple engineers are already testing prototypes for its successor. The early development roadmap focuses on two high-profile restorations: integrating Face ID beneath the cover glass and reviving the Action Button.

Restoring Invisible Biometric Authentication

The original foldable introduced refined hinge dampening, polished hover multitasking, and an expansive 7.6-inch inner canvas, but daily ergonomics took an unexpected step backward with the departure of Face ID. Replacing facial recognition with a side-mounted capacitive Touch ID sensor in the power button disrupted nearly a decade of ingrained iPhone habits.

On a device measuring 84.1 mm wide when folded and 164.6 mm when opened, reaching for a narrow side key requires deliberate hand adjustments. When holding the device with two hands to read, thumbs sit near the bottom edge rather than high on the rail, while left-handed users must blindly search with an index or middle finger. Capacitive sensors of this size are also notoriously sensitive to sweat or partial contact, making unlock failures frequent.

Apple adopted side Touch ID primarily because of extreme physical constraints. Unfolded, the chassis measures just 5.2 mm thick. With available internal depth hovering around 5 mm once the OLED panel, hinge mechanism, and chassis frame are accounted for, standard Face ID optical modules simply could not fit. Embedding under-display Face ID into the cover screen solves this friction, though engineering hurdles remain steep. Teardowns of the 8 mm thick iPhone 18 Pro show that Apple previously had to remove specific display pixels just to let light reach an under-display infrared camera, making implementation in a ultra-thin foldable shell even more complex.

Reclaiming the Hardware Shortcuts Cut for Thinness

Beyond biometrics, prototype testing aims to restore the customizable Action Button. The first-generation Duo made the polarizing choice to retain a specialized camera control key while dropping the Action Button entirely, stripping away blind-touch shortcuts for muting, flashlight toggling, or running automated scripts.

Camera capabilities also reflect thinness compromises. The debut Duo relies strictly on a main wide camera and an ultra-wide lens, using a 2x optical crop from the primary sensor for distance shots. Gurman noted that while a dedicated telephoto camera remains on Apple's internal wishlist, fitting optical depth into a 5.2 mm profile without creating an unruly camera bump remains an unresolved engineering challenge. Apple is also exploring slightly larger internal panels—roughly 7.9 or 8.1 inches—while deliberately avoiding oversized tablet proportions around 8.5 to 9 inches that would push the 254-gram chassis beyond pocketable limits.

Evaluating the Upgrade Timeline

Supply chain analyses from Ming-Chi Kuo and Bloomberg indicate that the second-generation model will not arrive until 2027, with larger form-factor revisions pushed toward 2028. Prospective buyers considering the current generation do not face immediate obsolescence, as official delivery delays are already easing and software developers are rapidly updating their layouts.

Major applications that initially opened with black pillarboxes have started rolling out optimized split-column views tailored to the 7.6-inch inner canvas. Ultimately, waiting comes down to individual priorities: those who depend on frictionless Face ID and physical action shortcuts may prefer to wait for the next generation, while users comfortable with Touch ID can safely embrace the current hardware as application support matures.

Would the absence of Face ID and a dedicated telephoto lens deter you from adopting a first-generation foldable, or is a 5.2 mm ultra-thin profile worth those hardware trade-offs?