some problem with PHP SESSION Array

session_test.php

<?php
session_start();
$_SESSION['IDNO']='A1234';
$_SESSION['DPT_COD'][0]='1402';
$_SESSION['DPT_COD'][1]='B402';
Print_r($_SESSION);
echo "<br /><a href=\"session_test2.php\">next!</a>";
?>

The browser show:
Array ( [IDNO] => A1234 [DPT_COD] => Array ( [0] => 1402 [1] => B402 ) )
next!

session_test2.php

<?php
session_start();
echo "Original SESSION array values:<br />";
Print_r($_SESSION);
echo "<br /><br />";

echo "New SESSION array values:<br />";
$IDNO='Z5678';
$DPT_COD='foobar';
Print_r($_SESSION);

session_unset();
session_destroy();
?>

In machine 1
The browser show:
Original SESSION array values:
Array ( [IDNO] => A1234 [DPT_COD] => Array ( [0] => 1402 [1] => B402 ) )

New SESSION array values:
Array ( [IDNO] => Z5678 [DPT_COD] => foobar )


In machine 2
The browser show:
Original SESSION array values:
Array ( [IDNO] => A1234 [DPT_COD] => Array ( [0] => 1402 [1] => B402 ) )

New SESSION array values:
Array ( [IDNO] => A1234 [DPT_COD] => Array ( [0] => 1402 [1] => B402 ) )


I think the result in machine 2 is what it should be.
But I don't know why macheine 1 show that diffrent result.

The answer is someone turn on register_globals in php.ini in machine 1.