Apple’s new iPhone Duo may have an unexpected drawback for anyone looking to buy a Vision Pro. The foldable phone doesn’t support Face ID, which means owners can’t use it to complete the facial scanning process required when ordering Apple’s mixed reality headset online.

The issue was highlighted by Bloomberg’s Mark Gurman, who pointed out on X that the iPhone Duo’s lack of Face ID creates an unusual compatibility problem within Apple’s own ecosystem. As shown in his post, Apple’s Vision Pro ordering process requires an iPhone or iPad with Face ID to scan the buyer’s face and determine the correct fit for the headset’s Light Seal and headband.

That means anyone using the iPhone Duo as their only Apple device could run into trouble when trying to purchase a Vision Pro online. Instead of completing the process on their phone, they’d need access to another compatible iPhone or iPad. Apple does offer an alternative, however, allowing customers without a Face ID-equipped device to book an in-store demonstration.

The discovery has sparked some amusing reactions on Reddit, with several users joking about how few people might actually be affected. One commenter wrote, “Those 3 Vision Pro users are going to be very upset when they hear about this,” while others pointed out that existing Vision Pro owners would likely already have completed the scanning process.

However, the discussion also raised a more practical concern. One Reddit user claiming to own a Vision Pro said they could no longer order replacement Light Seals or prescription inserts using their iPhone Duo, suggesting the limitation could also affect existing owners looking to purchase accessories. That claim hasn’t been independently verified, but it highlights how the missing Face ID hardware could create an inconvenience beyond the initial purchase.

It’s worth noting that Face ID isn’t required to use the Vision Pro itself. The restriction concerns the facial scanning process used when ordering the headset and certain accessories, rather than everyday operation.

For most iPhone Duo owners, this probably won’t be a major issue. Still, it’s an unusual oversight for two premium Apple products, particularly when buying one could require borrowing another device or visiting an Apple Store.