I've noticed that my pageview counts are being messed up by the pipe-lining feature in Firefox. People who visit using Firefox with pipelining enabled count two (or more) times for each visit.
What is the best way to detect or block these duplicate requests? I need to know how to block it on my server, not just how to disable pipelining in Firefox.
I'm using PHP and Apache.
Consider using a non-logfile based stats solution, like google analytics.
This is really an issue with your stats package of choice, not firefox.
You can use the Apache KeepAlive Off directive to prevent Apache from leaving connections open after a request.
If you're stuck on an older 1.3 version of Apache, it's KeepAlive 0.
Update:
The "Context" info on both these links reads "Server Config." According to this page, that means you can't use them in .htaccess files.
If you can only change settings from .htaccess, I think you will need to use the SetEnv directive to set the nokeepalive environment variable. The examples on that page also show how to set variables for only specific files/paths or specific browsers by user-agent.