There has been considerable buzz surrounding the much-anticipated foldable iPhone, with many expecting it to be branded as either iPhone Ultra or iPhone Fold. However, a fresh possibility has now surfaced online, suggesting the device could be called the iPhone Duo. There is currently no hard evidence confirming that Apple would adopt the iPhone Duo moniker, yet the naming does hold a degree of plausibility. Apple has previously leveraged the Duo branding, notably with the PowerBook Duo laptop series in the 1990s, and later with the MagSafe Duo charger introduced in the early 2020s. The term Duo would likely reference the dual-screen design of the foldable handset.

Historically, Microsoft launched a dual-screen Android phone in 2020 called the Surface Duo, which has since been discontinued, while Intel also popularized the Core Duo and Core 2 Duo processors during the 2000s. Given these past products, Apple may deliberately steer clear of the Duo name to avoid confusion. Nevertheless, competing brands are equally fond of similar terminologies, such as Samsung with its Galaxy S26 Ultra and Galaxy Z Fold8. In April, a former Macworld journalist, Felipe Esposito, cited sources familiar with Apple's plans, indicating that the foldable iPhone would be branded as iPhone Ultra. Bloomberg's Mark Gurman has also noted that many employees within Apple refer to the device as iPhone Ultra, although he has never definitively reported that this would serve as its official market name. Apple has regularly applied the Ultra label across its offerings, including the Apple Watch Ultra, CarPlay Ultra, and its line of M1 Ultra, M2 Ultra, M3 Ultra, and M5 Ultra chips.