same objects different behaviours?

I’ve this test scene in which I’ve created several test cases of my game.
Each test-case is made with a container-game object which has as children several game objects with prefabs and scripts used in the game.
Today I had to make a new one which is a variation of one I already had.
I selected the old one, duplicated it (tried both with ctrl+c/v and with ctrl+d), then disabled the old copy and hit “play” to check that it behaved the same way it should.
It didn’t.

I got nullreferences in a script, I don’t know why.

The question is: Is there anything that doesn’t get copied properly when you duplicate a gameobject inside unity? Are there any references that need to be updated?

update: if I hit play with enable=false and then I enable the copied gameobject manually, everything works fine.
What
The
Fuck
?