When you select a group of models in Studio and duplicate them then attempt to drag them all at once it only selects one of the models to move, this is a weird bug which happens every single time as when you duplicate it shows all of the models selected which you would think would then move all of them at once but no, instead it ignores the other 4 models and moves just the one.
I tested your suggestion and it does work but it’s weird because the normal selection just moves the objects you’ve selected, I think if two parts are inside of each other the selected one should always be selected.