Some redundancies are so common that few people notice them, but it’s worthwhile to be aware of them. A good example is “fellow classmate.” “Fellow” and “-mate” perform the same function. It’s better to say simply “classmate.”
The same is true of the equally redundant “fellow shipmate,” “ fellow roommate,” “fellow co-worker,” “fellow comrade,” and “fellow colleague.”
Even worse is “fellow peer.” Your fellows are your peers: same thing. The only people who should speak of fellow peers are members of the British peerage referring to others of their social class.