Independent routers don't isolate their middleware

router_test.js

var express = require('express');
var app = express();

var router1 = express.Router();
router1.use(function (req, res, next) {
    console.log('router1 middleware called.');
    next();
});

router1.get('/1', function (req, res) {
    res.send('1');
});

var router2 = express.Router();
router2.use(function (req, res, next) {
    console.log('router2 middleware called.');
    next();
});

router2.get('/2', function (req, res) {
    res.send('2');
});

app.use(router1);
app.use(router2);

app.listen(4000);

GET / prints both log statements.
GET /1 prints just the router1 statement.
GET /2 prints both log statements.

Can we add 2 or more middlewares on the same route ?