Description:
------------
Without the header() and imagegif() functions, the code is basically a hit counter script.  However, with the combination of those two lines of code, the hit counter will increment by 2.  Something is causing the script to run twice.

Reproduce code:
---------------
<?php

$site="test.txt";
$imageFile="image/metro.gif";
$hits=0;

if (file_exists($site)) {
	$temp=file($site);
	$hits=$temp[0];
}

$hits++;
	
$fileHandle=fopen($site, "w");
fputs($fileHandle, $hits);
fclose($fileHandle);

header("Content-type: image/gif");
imagegif(imagecreatefromgif($imageFile));
?>

Expected result:
----------------
test.txt should increment by 1 every time the script is accessed

Actual result:
--------------
test.txt increments by 2 every time the script is accessed