Door left open alert question

Configuration
1

I’ve got an alert that will notify me if a door has been left open for 5 minutes. My problem is that often (but not 100% of the time) I get an extra ‘left open’ alert when the door is finally closed. So the door gets closed and then I get both a ‘door left open for longer than 5 minutes’ and a ‘door has been closed’ alert back to back. Here’s the code I’m using for the alert. What have I mucked up?

garage_entry_door_left_open:
    name: The Garage Entry Door has been left open for over 5 minutes!
    message: "Garage Entry Door has been left open for over 5 minutes!"
    done_message: The Garage Entry Door is closed
    entity_id: binary_sensor.garage_entry_door
    state: "on"
    skip_first: true
    repeat: 5
    can_acknowledge: true
    notifiers:
      - mobile_app_iphonepro
2

Check the binary sensor history and see if the sensor is updating correctly and the double message is not caused by “slow update”