WhatsApp is testing the possibility of using the same user account on multiple devices.
As reported by WABetaInfo, the most recent beta version of WhatsApp includes a series of references to the ability to connect a single user account to a maximum of four devices, including PC and Mac.
WhatsApp should also allow users to send verification codes to access your account on an additional phone, even if it is not clear how this would be handled this function from the point of view of safety.
At present, WhatsApp requires a phone number to activate an iPhone and, although it is possible to use the device to connect to a desktop app or via the Web, it is not possible to use the same account on another phone without transferring the number, so if you lose that number, you lose your account WhatsApp.
This may change shortly, because it will be possible to connect other smartphones in the same way that currently we connect our account to WhatsApp Web.