Question Can I automate additional steps for "Duplicate"?

I don't see a way to combine both steps (duplicate track + replace gameobject references) into one single operation.

However, you can still add a custom menu entry to replace the binding of a track with a new gameobject. It would then be a two step process:
1- duplicate track
2- right-click on the new track, then select your custom action.

Here's a basic action to replace the binding of a track. It should show up in the context menu when right-clicking on a track.

Code (CSharp):

1. [MenuEntry("Replace binding with new GameObject")]
2. public class ReplaceBinding : TrackAction
3. {
4.     public override ActionValidity Validate(IEnumerable<TrackAsset> tracks)
5.     {
6.         return ActionValidity.Valid;
7.     }
8.  
9.     public override bool Execute(IEnumerable<TrackAsset> tracks)
10.     {
11.         foreach (TrackAsset track in tracks)
12.         {
13.             var newGameObject = new GameObject();
14.             Undo.RegisterCreatedObjectUndo(newGameObject, "Replace binding");
15.  
16.             PlayableDirector director = TimelineEditor.inspectedDirector;
17.             Undo.RecordObject(director, "Replace binding");
18.             director.SetGenericBinding(track, newGameObject);
19.         }
20.  
21.         return true;
22.     }
23.  
24.     //Uncomment this method to assign a shortcut to your action
25.     /*[TimelineShortcut("Replace binding", KeyCode.B)]
26.     public static void HandleShortCut(ShortcutArguments args)
27.     {
28.         Invoker.InvokeWithSelectedTracks<ReplaceBinding>();
29.     }*/
30. }