1) Create a timeline
2) Add a signal track bound to a gameobject
3) Add a signal Emitter, create a new signal and a new signal receiver
4) Set the Unity Event to Editor and Runtime, set the function to SendMessage
5) Set the PlayableDirector to Loop
6) Play the timeline

Result: The signal is emitted two times during a loop, once when the playhead passes the signal (correct) and again when the timeline begins a loop (incorrect).
Expected: The signal should not be emitted when the timeline begins another loop