I assume your 2nd listbox holds multiple items and therefore your posted listbox should be an array of items,e.g. $_POST['listbox2'][0], $_POST['listbox'][1], etc. Use a for or while loop until count($_POST['listbox']) to retrieve the items. Don't know if this will work - how is your 2nd listbox populated and are you multiselecting? I thought a simple listbox (select widget) just gave you the selected value on posting.

If you are posting to the same page (not recommended), then you will overwrite your $variable. Perhaps you could use a $_SESSION variable as a quick fix to hold this data?