If a client is logged-in from multiple browser , then faye by-default issue multi-client id for the same
it's difficult to send message and track user , do we have any solution to track the same
A Faye client is not the same thing as a user. Every Faye connection gets a different ID because messages are routed to connections, not users -- Faye doesn't know anything about what those connections are used for, and nor should it. You should also, as I've said many times here recently, not use the clientId for any of your business logic. Faye is just a message bus for routing data between actors in your application. Its clientId is an implementation detail and I will be restricting access to it in 1.0.
So, if you want to address a particular user, the common thing is send messages to a channel named for that user, and have any Faye connections acting on behalf of that user subscribe to that channel, with the server imposing whatever authentication mechanism your application requires.
It does not provide a way to 'track' people -- it only provides named channels and that's how you target messages to particular people.