Every node’s _ready() function is called once when that node enters the scene tree, so there should have been two prints if your scene contained the (scene with the) node with that script twice. If that was the case and it didn’t, maybe you were running the wrong scene?
I spent quite a while on this issue the other day and couldn’t figure it out.
As Hyvernox pointed out I expected the _ready function to be executed twice,
but it wasn’t. That is why I eventually posted on this forum for an answer.
Today (a good nights sleep and a reboot later) it IS beiing called twice.
I am not aware that anything changed, but apparently something has or I am doing something differently. In any case: the issue is gone now.