### Godot version

Master (4.2)

### System information

Windows 11 - Vulkan - Nvidia RTX 4070 - intel i5 13600KF

### Issue description

As you can see in the video when you try to add multiple scenes in to the 3D viewport (only with multiple scenes) the editor throws this error.

```
ERROR: Can't add child '@Node3D@18837' to '@SubViewport@9274', already has a parent '@SubViewport@9274'.
   at: (scene\main\node.cpp:1411)
```


Video: https://youtu.be/BVcCIigQJDw

This happens in the latest master (pulled on 2.11.2023).

### Steps to reproduce

Drag couple of the 3d mesh scenes into the 3D viewport and then select multiple scenes and drag them over and observer the error.

### Minimal reproduction project

[TestSceneDragAndDrop.zip](https://github.com/godotengine/godot/files/13253741/TestSceneDragAndDrop.zip)

for (int i = p_node->get_child_count() - 1; 0 <= i; --i) {
		Node3D *spatial_node = Object::cast_to<Node3D>(p_node->get_child(i));
		if (spatial_node) {
			spatial_node->update_gizmos();
		}
		_update_all_gizmos(p_node->get_child(i));
	}
}
void Node3DEditor::update_all_gizmos(Node *p_node) {
	if (!p_node && is_inside_tree()) {
		p_node = get_tree()->get_edited_scene_root();
	}
	if (!p_node) {
		/
		return;
	}
	_update_all_gizmos(p_node);
}
Object *Node3DEditor::_get_editor_data(Object *p_what) {