Trouble skipping before filter in controller


In my application I want several before filters to apply to every
request except for login and authenticate. So in my application
controller I have

before_filter :setup_user, :check_for_duplicate_user, :update_timestamp,

then in my user controller which contains the login and authenticate
actions i have

skip_before_filter :setup_user, :only => [:login, :authenticate]
skip_before_filter :check_for_duplicate_user, :only =>
[:login, :authenticate]
skip_before_filter :update_timestamp, :only => [:login, :authenticate]

however, when I call login or authenticate the before filters are not
being skipped. Can anyone think of a reason why?