title: WebSecurity.CurrentUserName returning username from other session
body: <p>I am new to ASP.Net MVC WebSecurity. </p>
  
  <p>Wondering how I make sure that WebSecurity.CurrentUserName returns user name of the current session. 
  I have seen a login code like before and I have a doubt on the session variable. </p>
  
  <p>Should I put unique value for each sesionPlaceholder? Will it resolve my problem.</p>
  
  <p>Thanks.</p>
  
  <pre><code> public bool Login(string username, string password)
      {
          // Validate credentials
          if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
              return false;
  
          bool credentialsAreValid = WebSecurity.Login(username, password);
          if (credentialsAreValid)
          {
              // Must add object to session in order to create a _persistent_ session id
              HttpContext.Current.Session.Add("sessionPlaceholder", "");
          }
          return credentialsAreValid;
      }
  </code></pre>