Apple's first foldable iPhone has revived a name Microsoft used for its own dual-screen phones. The iPhone Duo and Surface Duo sound related, but Engadget's comparison shows that they represent two different answers to the same basic question: how should a pocket device create more screen space?
The iPhone Duo is a clamshell foldable with one flexible display. It folds down for portability and opens into a larger conventional phone screen, following a design Android manufacturers have already established.
Microsoft's Duo was two screens, not one foldable panel
The original Surface Duo arrived in 2020 with two 5.6-inch displays joined by a 360-degree hinge. Users could run apps side by side, span some software across both screens or fold one display behind the other. Surface Duo 2 followed in 2021 with larger 5.8-inch panels, faster refresh rates and upgraded cameras.
That approach made the device unusually thin and useful for some forms of multitasking, but the hinge also split content down the middle. Engadget's reviews criticized unreliable software, awkward camera behavior and a design that was only adequate as a phone. Microsoft later canceled plans for a third generation, leaving the line discontinued.
The name has older Apple roots
Online jokes have treated iPhone Duo as a copy of Microsoft's branding, but Apple used the word decades earlier. The PowerBook Duo line ran from 1992 through 1997 and paired a compact portable computer with a dock that could turn it into a desktop setup. Apple also introduced the MagSafe Duo Charger in 2020.
That history does not make the iPhone Duo a technical descendant of the PowerBook. It does show why the shared name is less revealing than the hardware: Microsoft's Duo was a hinged pair of screens, while Apple's is a modern single-panel foldable.
