I have 2 numbers and both are using whatsapp. The problem with this is I have to carry 2 devices (smart phones) every where I go.
There are solutions to this by root your device and install some app that can cater for 2 numbers. But the solution is not that practical.
What I do is to use web.whatsapp.com to open both numbers. One is opened in Google Chrome. Another one is set to be opened in Firefox browser.
So when I’m working on my notebook (most of the time), it is very easy for me to check both whatsapp messages for both numbers.