### 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)

sun_environ_popup->hide();
	if (!p_already_added_environment && world_env_count == 0 && Input::get_singleton()->is_key_pressed(Key::SHIFT)) {
		/
		_add_environment_to_scene(true);
	}
	Node *base = get_tree()->get_edited_scene_root();
	if (!base) {
		/
		SceneTreeDock::get_singleton()->add_root_node(memnew(Node3D));
		base = get_tree()->get_edited_scene_root();
	}
	ERR_FAIL_NULL(base);
	Node *new_sun = preview_sun->duplicate();
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Add Preview Sun to Scene"));
	undo_redo->add_do_method(base, "add_child", new_sun, true);
	/
	/
	undo_redo->add_do_method(base, "move_child", new_sun, 0);
	undo_redo->add_do_method(new_sun, "set_owner", base);
	undo_redo->add_undo_method(base, "remove_child", new_sun);
	undo_redo->add_do_reference(new_sun);
	undo_redo->commit_action();
}
void Node3DEditor::_add_environment_to_scene(bool p_already_added_sun) {