You can use WhatsApp on your iPad with this app and you can also have 2 numbers of WhatsApp in your iPhone.
To connect you iPad to WhatsApp, simply open the app and see a QR code. Open WhatsApp on your iPhone, go to Settings --> WhatsApp web --> Scan QR Code and you are done!
Download the app! Start using WhatsApp on your iPad today!
Note: This is not an official application by WhatsApp Inc. Messenger is installed via in-app purchase.