This new feature lets you stay logged into and switch between both accounts on one machine.
Meta
The announcement, which wasalso posted on the company’s blog page, was met with excitement.
There is one caveat.

Two WhatsApp Accounts on one device.Meta
To have multiple WhatsApp accounts on the same unit, you’ll need an additionalSIM or an available eSIM.
fire up the configs in WhatsApp, then punch the arrow next to your name.
Tap Add account, and you’re done.
You’re able to manage privacy and notification controls for each account separately.