In the 2nd script (page) define your scripts as functions and "include" the script file in the begining of the first page using include(). Then just call the function you need when you need it.
Vary Simplified Example:
Scripts page 2 --- functions.inc
<?php
function printhello() {
print "Hello";
}
?>
MAIN PAGE 2: main.php
<head>
<?php
include("functions.inc");
?>
</head>
<body>
<?php
printhello();
?>
</body>
