I had a similar issue with my node server. It is due to the following bug in Chrome. In summary, Chrome is sending a request for a favicon on every request. As, is likely, you aren’t sending a favicon back, it requests one after every legitimate request.
Firefox, and most other browsers, also send out a request for a favicon when they first connect, but cache the result i.e. if there isn’t a favicon returned first time, they don’t keep trying – which is why you’re only seeing a single request from Firefox. It seems Chrome is unfortunately a little too persistent with its favicon requestiness.