[4.0 beta] Creating PackedScene duplicates its internal children

[atngames]

Godot version

4.0 beta

System information

linux

Issue description

Hi,
In the editor, I want to create a PackedScene from a branch of my Tree. This branch contains internal children. When I create the scene, its internal children remains but are duplicated with new non internal ones.

Steps to reproduce

Launch the minimal test project below

Create an InternalParent node
Right click on it and make it a Scene
Look at the new scene's tree and at the console output

I could not find how to avoid this behaviour.
Thanks for your help !

Minimal reproduction project

test_duplicate_internals.zip

[KoBeWi]

Looks the same as #54960, but no idea why this would happen. (that issue is still fixed, so this one might be something related to nodes created from script)

[Rindbee]

There is a solution to address this need:

func add_scene_specific_internal_child(node):
	if owner  and (owner.owner  or !scene_file_path.is_empty()):
		return
	add_child(node, false, INTERNAL_MODE_BACK)

Not suitable for inherited scene.