RSA then AD connection. How to autopopulate and keep the username ?

1- when view client connection, how to prevent the user to change the username (the RSA and AD ID are similar) ? I have put the Read-Only attribute in the logon page with no change. Perhaps in the view.inc ? but how ?

as mentioned you can't force it unchangeable, this is the view client behaviour which you don't control. you can ignore the first or second time the username is entered and only use one though.