Session Failures

[eluser]WanWizard[/eluser]
By default, every time you use $this->session->userdata(), the Session library does an automatic write, which creates a cookie.
So in itself it's not uncommon to have multiple entries for the same cookie (altough I don't like it, and I've changed that in my Session library).

What still points me in the direction of multiple requests is your last request.

Imagine you request a page, and in this page there's an image that doesn't exist, and causes a rewrite to index.php:
- browser requests the page, sends cookie with id C
- this request triggers an id rotation, C gets changed to D
- browser requests the page assets, one gets rewritten to index.php
- session C can't be found (because by now it's D), a new E is created
- browser now has a cookie with id E, D is overwritten by this new cookie.

So you really need to figure out where this second request is coming from. Check your webserver logs to see what exactly is requested. Alternatively, add a log_message('debug', $_SERVER['PHP_SELF']); to system/codeigniter/codeigniter.php, around line 162.