We haven't really seen any devices with more than one notch so far.
Android device manufacturers have jumped on the notched display bandwagon in droves.
Google said the move is to ensure consistency and app compatibility with devices that do have cutouts. It's also worth noting that this limit won't actually stop some "renegade" brands from building phones with three or more notches, considering the open-source nature of the Android platform.
In a blog on their developer's side, Google spelt out certain conditions that phone manufacturers should keep in mind to utilise the benefits of the notch support. The company explained how it had made it easier for developers to utilize the cutout area efficiently in Android P, and also encouraged them to test their apps using an Android P device or the Android Emulator before publication. By default, Android apps should function so that the status bar should be resized to be as tall as the notch, and app content should be display below that.
Aside from these stipulations, Google has stated that hardware manufacturers "can place cutouts wherever they want" on their devices. This second rule is to ensure no app content is displayed in the cutout area.
Like it or not, notched phones are here to stay, at least for the foreseeable future. "You won't see a cutout on the left or right long edge of the device", wrote Potoski.
In an effort to make sure that Android apps work across a variety of different devices, especially those that are starting to toy with design a bit more, the system is created to handle things automatically. Official support would make it possible for apps to register that a part of the screen is "cut out" and display accordingly. But it's always possible we see some insane designs with a lot of different notches from a manufacturer that doesn't have to follow those rules.
Phones with notches are incredibly divisive, but since Apple launched the iPhone X complete with a little screen cutout, there have been endless copies from other handset manufacturers.