Maybe a Bronze Cory. I doubt it is a Green variety of Corydoras aeneus. Such cute little guys!
They love to have friends, as you probably already know. The Albino aeneus is commonly found too, I have 5 Bronze and 2 Albino, they have paired by different color and hang out together. It's nice how the Albino really pop on the dark substrate.
A couple (5-8 years) of my older ones are a solid chunk 3 inches, tail is longer, so they can about double in size from when you usually get them in the lfs.