This question already has an answer here:
I'm currently developing in PHP, and I need to know if using
<?php session_start(); ?>
More than once in a script, or on a page/site will clear the variables or have any effect? If so how can I use this dynamically?
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From the PHP docs:
As of PHP 4.3.3, calling session_start() after the session was previously started will result in an error of level E_NOTICE. Also, the second session start will simply be ignored.