Round 2: (Brothers shared most HoF'ers) The Sullivan brothers? **Edit Hah! crap answer, just looked at their records!
You're beeing too hard on yourself - that's not the worst guess, I've ever seen (and they did share 2 HOFers: Dillon and Ketchel)!
That Al McCoy is not the Al McCoy who was the middleweight champion early in the 1900s. Your Al McCoy was from New England and later on fought Joe Louis as a heavyweight in 1940...
:goodal mcoy is the second on at list thst one of my favourites, jock mcavoy, fought on his trip to the states
Quite a few more! But Dundee was a better answer, than you may realize - as you had left out Solly Krieger, Ben Jerby and Marcel Thil! Al McCoy, on the other hand, (as has already been pointed out by Burt) was not the "real" McCoy... so, Dundee's list of middleweight champs actually looks like this: Steele Risko Yarosz Jerby Brouillard Overlin Krieger Thil That's 8 - but still a few short of what we're looking for. But you're really very, very close as we're talking about someone from the same period.
Maybe Freddie Steele: Al Hostak Solly Krieger Fred Apostoli Ken Overlin Babe Risko Gorilla Jones Vince Dundee Ceferino Garcia
No... not Steele either. Hint: Our man was a non-champion, whose name seems to pop up on the record of just about every middleweight champ of his time - 11 to be exact!
Yes, hh... Pirrone is the answer. But would you mind terribly, sharing the honours with D.T - who has put in several hours of hard work on this question?