Help, How can I download 2 whatsapps on windows phone

I Have look all over the web and forums but couldn't find my answer.. I just got the nokia Lumia 640 XL dual sim and I wanted to download 2 separated whatsapps each for my different number on the same windows phone..
Please Note that Im a noob when it comes to windows phone this is my first and I still haven't got the terminology down..
thanks for you help and time..