Hello.

You have a slot named head with an image inside.
You duplicate it. So now you have a slot named head2 by default.
Then head2 is automatically selected. Proof, you can see the selection in the Hierarchy. It's highlighted.

But, if you move if with the translate tool, it's the original head that you moved. Not the head2 as you thought it would be. Sometimes it's boring when you start positioning images.

It works fine when you duplicate a bone, but not a slot.

Thanks! Oh sorry, I didn't mention I was under 3.5.51.
Can't wait for the awesome 3.6 big realease

Yeah no worries. I just remind I didn't give proper informations on my configuration and which version I was using. As asked in the Bug Posting Guidelines