Before we begin, you need:
A Jailbroken iPhone.
iFile app installed on your iPhone.
Little technical knowledge and some patience.
How to Run Two WhatsApp Accounts on iPhone:
Open iFile from app drawer of your iPhone.
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Go to Settings-> File Manager-> enable “Application
Names“.
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Head over to /var/mobile/Applications/ and find
WhatsApp.
Applications are shown as Alphanumeric directories. Find
WhatsApp directory and copy paste the same folder in
Application folder itself. You’ll get two folder with same
name.
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Open the WhatsApp directory you just pasted, select
WhatsApp.app folder and search for the Info.plist.
Open the Info.plist using the Property List Viewer and
search for “ CFBundleIdentifier”. You just need to add “2”
at the end.
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It’s time to save the changes and reboot your iPhone. Wait
for a minute and finally you’ll be seeing a duplicate
WhatsApp icon on your Homescreen.
Voila! You are all set to run two WhatsApp accounts on
iPhone.

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Facing any problem?Let me know.