### 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)

return p_node->get_meta("_edit_lock_", false);
}
void Node3DEditorViewport::_list_select(Ref<InputEventMouseButton> b) {
	_find_items_at_pos(b->get_position(), selection_results, spatial_editor->get_tool_mode() == Node3DEditor::TOOL_MODE_SELECT);
	Node *scene = EditorNode::get_singleton()->get_edited_scene();
	for (int i = 0; i < selection_results.size(); i++) {
		Node3D *item = selection_results[i].item;
		if (item != scene && item->get_owner() != scene && item != scene->get_deepest_editable_node(item)) {
			
			selection_results.remove_at(i);
			i--;
		}
	}
	clicked_wants_append = b->is_shift_pressed();
	if (selection_results.size() == 1) {
		clicked = selection_results[0].item->get_instance_id();
		selection_results.clear();
		if (clicked.is_valid()) {
			_select_clicked(spatial_editor->get_tool_mode() == Node3DEditor::TOOL_MODE_SELECT);
		}
	} else if (!selection_results.is_empty()) {
		NodePath root_path = get_tree()->get_edited_scene_root()->get_path();
		StringName root_name = root_path.get_name(root_path.get_name_count() - 1);
		for (int i = 0; i < selection_results.size(); i++) {
			Node3D *spat = selection_results[i].item;
			Ref<Texture2D> icon = EditorNode::get_singleton()->get_object_icon(spat, "Node");
			String node_path = "/" + root_name + "/" + root_path.rel_path_to(spat->get_path());
			int locked = 0;
			if (_is_node_locked(spat)) {