In the current version of iOS 12 beta, there are hints in the code that indicate a dual-SIM feature / capability.
A feature which was rumored about since the beginning of the year looks like to be “confirmed” by a part of the code in iOS 12 beta 5. A new iPhone X Plus is rumored to include a 6.5-inch OLED display and dual-SIM support in certain regions. According to a report from 9to5Mac, the latest iOS 12 beta, beta 5, includes references to a dual-SIM feature. To be more precise, the system refers to a physical second SIM. This means that an iPhone with dual-SIM support might not be restricted to a single SIM tray and eSIM support.
This is not the first time an upcoming feature has been spotted in the code. A while ago, the firmware for the Apple HomePod revealed how the screen of the iPhone X will look like. Beta builds of iOS 11 included Face ID, Animoji, and updated AirPods before Apple even announced them. The latest iOS 12 beta has also revealed the new AirPods wireless charging case might be ready to be released.
It is expected that Apple will hold their annual iPhone even sometime in September. There are plenty of rumors around the launch, as many are expecting a new iPhone X Plus. According to rumors, the phone will feature a 6.5-inch OLED display, alongside a 6.1-inch LCD model and a refresh to the 5.8-inch iPhone X.
Dual-SIM is a very popular feature in some markets, mostly emerging ones.