I use MAMP Pro to manage my local virtual hosts. It’s about a hundred times more convenient than Apple’s “native” Apache/PHP install (unfortunately a sad truth).
One annoying facet, though, is that MAMP will force its favicon when you’re using a MAMP-managed virtual host. Here’s how to get rid of this “feature” and reclaim your presumably awesome favicon.
First, make sure MAMP is not running Apache. Then, go to File > Edit Template > Apache httpd.conf
Once you’ve got the configuration file open, look for the line (roughly 625 for me):
Alias /favicon.ico "/Applications/MAMP/bin/favicon.ico"
and comment it out with a hash (#). Save your configuration, then reboot MAMP’s Apache server. You might have to flush your browser’s cache before it recognises your own favicons.
This took way too long to fix, so I hope this helped someone else.