Two websocket override session value

I make two web application which listen on port 1234 and 5678. (I am using Express js)

And I store some session value while login. Suppose I store some string (like :"person1") in session while login on first application(on port 1234), Then I store some string (like : "person2") in session while login on second application(on port 5678). When person2 login in second application at that time it destroy session of first application (!!?) then if I refresh page, it loggedout due to session destroy.

Server side connection (First application which listen on port 1234)

var express = require('express'),
    sio = require('socket.io');

app = express.createServer();

app.configure('development', function(){
app.use(express.bodyParser());
app.use(express.cookieParser());
app.use(express.session({secret: "hello1"}));
    app.use(express.static(__dirname + '/'));
    app.set('views', __dirname + '/views');
    app.use(express.errorHandler({dumpExceptions: true, showStack: true}));
    app.use(app.router);
});

app.listen(1234);
app.get('/login', function (req, res) {
    req.session.uName = req.body.uName;
    .
    .
    .
    .
    .
});
var io = sio.listen(app);

Server side connection (second application which listen on port 5678)

app.get('/login', function (req, res) {
    req.session.uName = req.body.uName;
    .
    .
    .
    .
    .
});
app.listen(5678);
var io = sio.listen(app);

=========================================================================

Client side connection (first application [1234])

<script type="text/javascript" src="/socket.io/socket.io.js" ></script>
<script>
      var socket = io.connect("http://"+mylocalip+":1234");
</script>

Client side connection (second application [5678])

<script type="text/javascript" src="/socket.io/socket.io.js" ></script>
<script>
      var socket = io.connect("http://"+mylocalip+":5678");
</script>

Please Help Me ...

Thanks in advance.