I can try preventing this submit, using javascript or even session. But, this being a multi-server architecture, session variable that is present in one server is not visible to the other one.
Bala,
I dont understand how one user is so tightly coupled to the other user. Is it clustered servers ? in that case session migration is there and session variable is visible to other servers , but its costly and hence you got to minimize the variables in session.
Javascript ? Do you mean disabling submit . thats not the proper solution for this.
Is that expected behavior ? Check if you use any instance variables , which is shared among threads , hence needs to be synchronized.