How to redirect this?

[andrewshim]

A year ago, oblivious to the duplicate content penalty, I added a variable to my most busy page changing it from :

idea.php?variable1=example1

to

idea.php?variable1=example1&variable2=example2

Now, obviously these two URLs point to the same page. It's just that the extra variable was added to enable some internal processing.

Am I correct to assume that I can make a 301 redirect using PHP from

idea.php?variable1=example1

to

idea.php?variable1=example1&variable2=example2

?
There are approximately 500 URLs involved.

[Habtom]

<?php
// Permanent (301) redirection
header("HTTP/1.1 301 Moved Permanently");
header("Location: http://www.example.com/idea.php?variable1=example1&variable2=example2");
exit();
?>