jinput->get doesn't consistently return a particular URL parameter

Question

I have a php page that processes 2 parameters on the URL that calls it. I can't figure out why jinput->get works sometimes but not every time. The code is:

$jinput = JFactory::getApplication()->input;
$source = $jinput->get('source', "", 'string');
$volume = $jinput->get('volume', "", 'string');

and the following URLs work only if the previous URL had a different volume number:

Example:

URL 1.
http://ilfvgs.org/index.php/online-data/mi/volume?source=IN&volume=13,%2303 works fine returning the correct $volume = "13,#03"

URL 2. http://ilfvgs.org/index.php/online-data/mi/volume?source=IN&volume=13,%2306 works but not if it is used just after URL 1. If this call came after URL 1., jinput->get() returns $volume = "13,#03" instead of "13,#06"

If the volume is changed to "14,#02", it will work correctly (unless the previous call was for "14,#01"). So it appears that the volume parameter is only getting reloaded if the number at the start of the volume (e.g. 13 or 14) changes!

This fails regardless of the numbers involved. For example the same thing occurs if the volume is "10,#1" and "10,#2" for URL 1, and 2 (using an appropriate source).

Using Joomla! 2.5.16

Answer 1

It could be due to some caching, where the code is executed again only for a "different" request - caching plugin may have a bug that they don't differentiate elements in URL after the comma

Answer 2

It appears there is a bug in the Joomla caching plugin that doesn't refresh if the it thinks the URL has not changed. It apparently does not process the URL beyond a "#" character. I verified this by removing the "#" from the URL parameter (and then adding it back to make the following database query work) and the URL parameter was correctly updated every time. Thanks to Marko D for suggesting it might not be processing the parameter after the "," which was the right idea but not the right character.