True Brahmas come in 3 recognized colors. Light , dark and buff. The Light and Buff varieties are the columbian color pattern; have a basically solid color feathered body, with black tails, and black feathers laced with the appropriate color (either white for the lights or buff for the buffs) in the saddles and hackles of the males, and on the feathers down the toes. The Darks are the silver pencilled color pattern, the males resemble the silver duckwing in the old english somewhat, the females have feathers that are pencilled with alternating black and silvery white. Hard to describe the color pattern if you have never seen it. All Brahmas have a pea comb, like a rose comb but it doesn't stand up off the head in the back with a spike, and is smaller.
Any thing that you got, that has a single comb is not a true brahma. They should also have feathers on both the outside and middle toe. They do not have crests so if there is any poofyness when it gets in the adult feathers, it also is not a true brahma.