I think it's the same puppy. I have pictures of Zoe from her breeder, then from when I got her and it looks like 2 different pups. But I know it's the same; she was the only girl in the litter. NO way to switch pups!!
Also, I compare pictures of her that I took and I would swear it was 2 different pups if I didn't know better. And get this, now she seems to be changing colors again...at 1 1/2 years old. She was black as a pup, then blond/silver, and now her roots seem to be black again.
In the end, all that matter is you love the baby you have!