duplicate selection of variable

gistfile1.txt

infra:~ # cf-agent -KI
 !! Duplicate selection of value for variable "missing" in scope dead_hosts
 !! Rule from /var/cfengine/inputs/actions/update.cf at/before line 38
 !! Duplicate selection of value for variable "missing" in scope dead_hosts
 !! Rule from /var/cfengine/inputs/actions/update.cf at/before line 38

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bundle agent dead_hosts {
vars:
    "delay" int => "24";

    # Allow the variable to be set to a different value on subsequent pass
    "missing" slist => { hostsseen ("$(delay)","notseen","name") },
              policy => "free";

   # Only set the missing list once
  !first_class_pass::
    "missing" slist => { hostsseen ("$(delay)","notseen","name") };

classes:
  any::
    "first_class_pass" expression => "any";

reports:
    cfengine3::
        "I haven't seen $(missing) for the last $(delay) hours!"
            action => if_elapsed("240"); # every 4h
}
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