For a second request from a different browser, will a unique session id be created?
I think more appropriate question to be asked, is "will server create a new session for second request"?
First of all server will not know whether it's second or first request. For server, every request is afresh. But to make the request-response conversational, server creates a http session and attaches a unique id for that session with the particular response. And server does it implicitly by setting a cookie. So when a request comes in, server will check if there is any session id with the request, if not server will create one.
Does that help?
maybe I am saying same thing again and again, but I find it difficult to put it in any other way