$_GET strings seperation

Hello Everyone, I have a problem with GET strings. I use $_SERVER["REDIRECT_QUERY_STRING"] to get the value-pairs in the URL. The problem is that there is a cID variable that keeps appending itself to the string continuously everytime someone clicks on a different category link on the website. For example, instead of this: http://www.someexample.com/admin/index.html?cID=42&somevar=value&somevar2=value2 it keeps appending another cID to it everytime it goes to a different link, like this: http://www.someexample.com/admin/index.html?cID=42&cID=39&cID=44&cID=37&somevar=value&somevar2=value2 I know that this is happening because I'm appending it with the dot (.) but is there a way to just inject a single cID and still have the rest of the value-pairs available? Something built into PHP, maybe a different predefined variable I don't know about? Or, do I have to make a complex function to separate each out and then put it back together again like humpty dumpty? Is there an easier way to do this and still have a single cID variable in the GET string? Thanks in advance.