PHP session variable changes between pages

Question

I have a session variable that I set like this:

Answer 1

The only solution I can think of is that you are making a second request to the first page without knowing it. You should probably check your apache access log for this second access...

Making a simple request counter would be another solution to check this:

$_SESSION['counter'] = isset($_SESSION['counter'])? $_SESSION['counter'] +1 : 0;