For some reason the IUserIdentity.Authenticate method is being called twice in my set up. I am wondering if this is a by design, or if I have something wrong in my set up.
My problem is that I have to track when a user Logs in and when he logs out. Based on the current behavior every user is logging in twice and logging out once.
your response pointed me in the right direction. I was focusing on the Model, and the issue was in the View and Controller. Basically the log in form had enableAjaxValidation=true, which caused 2 calls on the model. Once I set enableAjaxValidation=false then the issue went away.