Returned Lowepro AW Mini Trekker

It comes with a daypack??? I'm confused. I thought it was just one pack. Is it one pack with another smaller pack attached, or is it a belt pack with a daypack on top?

No you get the big backpack and a small bag that can be strapped onto the backpack.

Heh, the daypack is my only quibble with the Nature Trekker. It is a pain to attach and remove (a set of four double D ring attachment points and straps). The main bag on its own juts out pretty far from your back, add the daypack and you can wipe out half a room by turning around.
Plus, I manage to load up the main bag pretty thoroughly and attach my tripod. The added weight of tossing even more items (even lighter stuff like a lunch, change of clothes or jacket) on top of that into the daypack makes me wish for a few Sherpas. The daypack is handy, just need some common sense as to how much you want to carry.