Method 1:
1.Download the GBWhatsApp apk file and install it in your mobile.No need to uninstall your previous version of WhatsApp from your mobile.
2.As the official WhatsApp it also asks to accept the terms and conditions to install,so tap Agree and continue.
3.After that enter the mobile number which you want to use as secondary and tap ok.Once you tap ok,automatically you will receive verification code to the number.Enter the code to get your number verified.
4.Once your number gets verified you can see profile info screen,just set your profile name and picture and tap next.Automatically your secondary WhatsApp account will get configured as the regular account.
5.Now you can see two WhatsApp icons with different accounts in your mobile.
Method 2:
1.Open the WhatsApp folder in your mobile and just rename it as OGWhatsApp.
2.After renaming the folder uninstall the official version of WhatsApp from your mobile.Make sure to backup your conversations before uninstalling so that you can restore the conversations back if you need.
3.Now download the OGWhatsApp apk file and install it.After installation it will ask your number for confirmation,here you have to give your old number which you had used in official WhatsApp account and then click ok.Be sure to enter your previously used number and continue the verification process.
4.Now again download the official version of WhatsApp from Play store and install it.Here you can enter the alternate mobile number which you wish to use as secondary one and click ok to complete the verification step.
5.That’s it now you can use two WhatsApp accounts in one mobile without rooting your mobile or losing your data.