Apple's second-generation iPhone Duo may feature Face ID, according to Bloomberg's Mark Gurman. Prototypes are reportedly being tested with Face ID technology integrated beneath the display. The current iPhone Duo uses a side-button fingerprint sensor due to space constraints. Adding Face ID would require smaller depth-sensing components and advancements in AI. Apple is also considering an Action button for future iPhone Duo models. These upgrades are anticipated for a successor expected next fall. However, the company has not yet finalized the inclusion of Face ID. The first-generation iPhone Duo launches at $1,999. Its thin design presents a challenge for accommodating Face ID hardware. These potential enhancements reflect ongoing development for Apple's foldable device.