Know their names? The early bird gets the worm .

[bzkfn]

These are the ones I know:

Leon & Michael Spinks
Gabriel & Rafael Ruelas
Tommy & Mike Gibbons
Donald & Bruce Curry
Max & Buddy Baer

McCrory I would assume is Glenn...but I didn't think he had a boxing brother

[Spicoli]

Michael and Leon
Tommy and Mike
Gabe and Rafa
Khaosai and Khaokar aka I'm not my brother, I swear
Chana and someother guy
Buddy and Maximillian
Mike and Tony
Donald and Bruce
Milton and Steve
Jerry and Mike aka Jeezus Bob, why so damn hard!!
I'll toss in Gaby and Orlando Canizales cause they were bad ass

[beenKOed]

Michael and Leon
Tommy and Mike
Gabe and Rafa
Khaosai and Khaokar aka I'm not my brother, I swear
Chana and someother guy
Buddy and Maximillian
Mike and Tony
Donald and Bruce
Milton and Steve
Jerry and Mike aka Jeezus Bob, why so damn hard!!
I'll toss in Gaby and Orlando Canizales cause they were bad ass

I'll give you the second first name for the last name Porpaoin. Songkram
I added Canizales to the thread. You are the man.

[Master]

Did Henry Cooper have a twin brother that boxed?

[roberto duran legend]

Did Henry Cooper have a twin brother that boxed?

Yes he did mate, his record is not that impressive 16-14-1.George Cooper.

[Vendettos]

Did Henry Cooper have a twin brother that boxed?

Yes he did mate, his record is not that impressive 16-14-1.George Cooper.

Still not completely awful. If you're + you did well.

[CutMeMick]

Brothers who are boxers. I give you last names, you supply the first names.
Spinks
Gibbons
Ruelas
Galaxy
Porpaoin
Baer
Ayala
Curry
McCrory
Quarry
Canizales

You also have the:
Kameda
Marquez
Matthysse
Arce
Vanderpool
Tiozzo
Rocchigiani
Branco
Haradas
Solis
Montiel
Gatti
Alvarez
Donaire
Chavez
Diaz
Penalosa
Garcia (twin bros)
Arredondo
Carbajal

Try those...
Cotto