Yo dawg, I heard you like lockboxes so I put a lockbox inside your lockbox.
I wondered how many nested lockboxes I would find. Were they like those stacked Russian dolls, with each lockbox smaller than the one before? Alas, the were some cloth bracers inside the next one, so it ended after a single iteration. I'd have loved this when one actually had to level up lock picking as a skill.
I am curious to know if this is a bug, or if somebody at Blizzard development slipped it in as a joke. Anyone who plays this game knows that the developers have a sense of humour, so you never know.