Hehe, yes, I'd guess that is the nearly universal sedimentation of stuff in warehouses =) It starts with the common 'well, I don't throw this thing away yet, maybe I'll need it again in the near future'. And then new stuff gets stored next to / on top of the older stuff, until no-one remembers what exactly there is.

In Finland I've seen people using old horse collars as a mirror frame. I don't know if the tack you found has any parts which could find a new life =)