same form data, different actions on two separate submit buttons

Question

I have what is essentially a shopping cart that needs to have two separate checkout options. The first of which takes the user away from the site, but form data must be post

Answer 1

you could set an onclick handler to the buttons and change the form action dinamically.
I'm giving this answer because you have the javascript tag and i assume the external site receives the parameters via POST METHOD so you could not make a redirection in php

But i wouldn't trust in this because it require the users having javascript enabled...