I can explain that, it's based on local post compliance laws.
The manufacturer already supplies it in the middle box, which is a valid parcel packaging for their country. However, when it's being delivered in yours, that one is not allowed so they need to pack it up again in another box, the bottom one, that is an allowed packaging in your country.
This stuff can be absurd at times. And go really wild.
Source: Worked in a wine shop for a few years that sent and received a lot of wine internationally via mail.
Usually it's something about material types or thickness.
The weirdest packaging I've seen before was a bottle in a shipping box, inside another leak-proof box inside another non-leak-proof box.
The reason went as this:
It was sent in the first box, which had cushioning so the bottle isn't damaged in transit.
It went through an export company that wanted to be helpful and added a leak proof extra box.
Unlike the first box, this second one was not an acceptable type of box in the recipient country, so they wrapped it again.
And due to laws, usually it is now legally possible to take away any box, effectively replacing it. You're not allowed to open/unseal other people's mail basically.