Godot version

v4.0.beta.custom_build [afe1c89]

System information

Windows 10

Issue description

Making a separate a issue from my comment on #68865 to make it easier to fix.

If a scene or elements from a scene are already loaded, one will be unable to instantiate it again.

This was not a problem before the merge of #67714 .

Steps to reproduce

To make it easier to understand how to trigger, here's the scene tree:

The script is in the "2nd_child" scene.

Minimal reproduction project

MRP:
preload problem 4.x.zip