Make a function register2--something like:
function register2($formelement1, $formelement2) {
// Register code here
}
And near the bottom of the script have:
switch ($action) {
default:
index();
break;
case "register":
register();
break;
case "register2":
register2($formelement1, $formelement2);
break;
}
Change $formelement1 and $formelement2 to the form names used in your HTML, and add more if you need.