I thought I had answered this question before thanks to StackOverFlow, but I hastily took an answer and it turns out not to be the real cause to my problem.
I have checked my Apache Access Log:
This is me browsing my web app on Google Chrome Browser.
127.0.0.1 - - [06/Jan/2010:22:17:35 +0000] "GET /webs/end/new.php HTTP/1.1" 200 2146
127.0.0.1 - - [06/Jan/2010:22:17:36 +0000] "GET /webs/end/settings.php HTTP/1.1" 200 4548
127.0.0.1 - - [06/Jan/2010:22:17:38 +0000] "GET /webs/end/index.php HTTP/1.1" 200 2042
This is me browsing my web app on IE7.
127.0.0.1 - - [06/Jan/2010:22:21:49 +0000] "GET /webs/end/settings.php HTTP/1.1" 200 4548
127.0.0.1 - - [06/Jan/2010:22:21:50 +0000] "GET /webs/end/index.php HTTP/1.1" 200 2042
This is me browsing my web app on Firefox.
127.0.0.1 - - [06/Jan/2010:22:18:08 +0000] "GET /webs/end/settings.php HTTP/1.1" 200 4548
127.0.0.1 - - [06/Jan/2010:22:18:09 +0000] "GET /webs/end/settings.php HTTP/1.1" 200 4548
127.0.0.1 - - [06/Jan/2010:22:18:10 +0000] "GET /webs/end/index.php HTTP/1.1" 200 2042
127.0.0.1 - - [06/Jan/2010:22:18:10 +0000] "GET /webs/end/index.php HTTP/1.1" 200 2042
127.0.0.1 - - [06/Jan/2010:22:18:11 +0000] "GET /webs/end/new.php HTTP/1.1" 200 2146
127.0.0.1 - - [06/Jan/2010:22:18:12 +0000] "GET /webs/end/new.php HTTP/1.1" 200 2146
This is just me clicking around. But notice that for every page request firefox seems to be loading the page twice and its effecting my PHP scripts as they are executing twice and making two insertions into my DB!
Why is the case? I am using Firefox 3.5.6. I am guessing this is a Firefox issue rather than a PHP/Apache one?
What plugins have you got installed in Firefox, they may be making requests silently, especially FireBug. Try turning firebug off & see if it still happens.
As mentioned in the comment below, the latest version of FireBug shouldn’t be doing this, so if it isn’t, try disabling all your plugins (or running FireFox in safe mode) and see if it still happens