Sending form to two php files

Using PHP: You can send via post or get to a file (controller), which will handle and distribute the data to the 2 different models.

Using JAVASCRIPT: You can get the fields you want and send (via post or get) to different files via AJAX.

I hope I have helped.

As Alan said, this is possible via AJAX.

Even though I do not know your needs, I can say that the most "cheap" will always be to do the entire processing in a single PHP server-side script.