Microsoft's 2009 Courier prototype anticipated the "iPhone Duo" concept

Technology enthusiasts may find a striking resemblance between the "iPhone Duo" concept and a prototype device from 2009 known as the Microsoft Courier. Although Microsoft never progressed past the prototype stage and abandoned the project less than a year later, the similarities in their integrated user interfaces remain remarkable.

A key aspect of a proper foldable smartphone is the clever integration between hardware and software. A prime example of this is the ability to drag a portion of a photo from one side of the screen to a separate application on the other side. Interestingly, Microsoft demonstrated a highly similar capability in its 2009 Courier concept video.

While Microsoft eventually incorporated some of this type of capability into its Surface line of products, it is notable that Apple has been the one to truly match the level of integration that Microsoft originally envisioned over a decade ago.