Javascript, list menu , php

Heya!

I have two list and with a javascript function the user can move information between the list. If you want an example:

http://javascript.internet.com/forms/form-swapper-2.html

then when user submit the form, i want to save the information in db that list2 have, but how can i know which items are in list2?
I only know which item was selected not all items in list… :frowning:

any sugestion ???

thks