Double request when chrome developer tools open

问题

I've an odd problem, i have a very simple node/expressjs app ( i have a much more complex one but this simple example shows the problem ). This app has three routes as shown here:

var i = 0;

app.route('/login')
.get(function(req, res){
    console.log('login', ++i);

    res.send('login');
})

app.route('/test')
.get(function(req, res){
    console.log('test', ++i);

    res.send('test');
})

app.route('/')
.get(function(req, res){
    console.log('index', ++i);

    res.send('index');
})

Pretty simple. Any time one of these routes is requested 'i' is incremented and logged, and it works fine, except when the chrome dev tools is open. When the dev tools are open requesting either login or test will be requested twice. Here is the results of the log:

15:45:30 web.1  | index 1
15:45:33 web.1  | login 2
15:45:34 web.1  | login 3
15:45:37 web.1  | test 4
15:45:37 web.1  | test 5
15:45:41 web.1  | login 6
15:45:42 web.1  | login 7
15:45:45 web.1  | test 8
15:45:45 web.1  | test 9
15:45:48 web.1  | index 10

Whats going on here. Is it a Chrome bug?

Adam