can i use two watsapp apps for the two different sims on the iphone?

This is an official answer from the developer's site:--> https://faq.whatsapp.com/general/verification/using-one-whatsapp-account-on-multiple-phones-or-with-multiple-phone-numbers/

For any further question about that 3rd party application, please visit WhatsApp support site.

Regards

Giulio

As far as I know WhatsApp is yet to launch this service. However, contact the app developer here --> App Support or WhatsApp FAQ