Thanks, I've actually browse through these 2 sites before posting. It resembles Corydoras pulcher but the dots pattern on the body is not uniform in straight line.
Also got a few of this, not sure about it's ID also
It has a nice dark blue coloration from head to almost 3/5 of the body and then gradually turn Yellow towards the tail. Very very active...
I would say that the cory in the second picture is an atropersonata. I bought 6 or 7 of them from Frank Falcone a while back and they look identical to yours. Good luck with it.
The one on the third picture almost looks like an emerald cory.
You could try calling the store that you bought them from and have them check there supplier to see what they ship out. This may help you to narrow down an identification.