Each bar is wrapped in cellophane, which are then wrapped in the normal outer packaging. To make the 4 pack, they simply took 2x two packs and put them on a cardboard tray,and then wrapped those.
I don’t think I’ve ever gone through so much unwrapping for candy.
Chocolate bars used to be folded aluminium foil and paper. Some still use those materials but now they weld (crimp with enough pressure?) the foil which is probably better for the product but OTOH it’s slightly annoying because you have too little foil to re-wrap a bar you only took a little bit off of.