### Godot version

4.2 dev3

### System information

Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1060 (NVIDIA; 30.0.15.1403) - Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz (8 Threads)

### Issue description

If you have a Method Track with multiple calls to the same method, they are joined together and makes things unreadable:
![image](https://github.com/godotengine/godot/assets/2223172/a2ab8446-28a1-440b-b0d5-5049f5d705b4)
The horizontal line shouldn't be used here. I think it might be a regression.

### Steps to reproduce

1. Add AnimationPlayer
2. Add a Method Track (with Add Track button)
3. Add some key to the track
4. Add another key with the same method

### Minimal reproduction project

N/A
EditorNode::get_singleton()->show_warning(
			TTR("This animation belongs to an imported scene, so changes to imported tracks will not be saved.\n\nTo modify this animation, navigate to the scene's Advanced Import settings and select the animation.\nSome options, including looping, are available here. To add custom tracks, enable \"Save To File\" and\n\"Keep Custom Tracks\"."),
			TTR("Warning: Editing imported animation"));
}
void AnimationTrackEditor::_select_all_tracks_for_copy() {
	TreeItem *track = track_copy_select->get_root()->get_first_child();
	if (!track) {
		return;
	}
	bool all_selected = true;
	while (track) {
		if (!track->is_checked(0)) {
			all_selected = false;
		}
		track = track->get_next();
	}
	track = track_copy_select->get_root()->get_first_child();
	while (track) {
		track->set_checked(0, !all_selected);
		track = track->get_next();
	}
}
void AnimationTrackEditor::_bind_methods() {