Whitaker and Stevie Johnston had different styles completely. An obvious one is JC Chavez and JL Castillo. Only Castillo was a VERY poor man's Chavez. Joshua Clottey and Marlon Starling. Starling was way better though. Carlos Ortiz fought a bit like Joe Louis. Except he didnt have the punch of Louis, but he was a more fluid boxer than the Brown Bomber.
Barney Ross and Oscar de la Hoya. Henry Armstrong and Frankie Warren. Muhammad Ali and Jose Legra. Duilio Loi and Santos Laciar. German Torres and Jose Luis Ramirez. Lupe Pintor and Jose Medel. Benny Leonard and Tommy Loughran. Jung Koo Chang and Roberto Duran.
German torres is an underrated fighter.With his power, chin and steady aggression he'd be a very good underdog bet against carbajal or Lopez i think. I can think of a few groups of fighters i'd consider very similar, not just pairs. Ismael Laguna, Ernesto marcel and Eusebio Pedroza had very similar traits. Rodolfo Gato Gonzalez, Jose Napoles and John Conteh.the last two even looked a lot like each other. Howard Winstone and Masao Ohba Jorge Ahumada and Galindez Khaosai and Khaokor galaxy Chatchai Sasakul and Daorung Chuvatana Nana Konadu and Ike Quartey Horacio Accavallo and Alberto Davila Monzon and Cervantes to an extent, though Cervantes was nowhere near as good at fighting tall against fighters that made him lead. Strictly defensively, Whitaker and Zapata used a lot of similar unorthodox angles and low crouching moves.Canto and Kalambay were quite similar as well, though all these fighters were a lot different offensively.
Thomas Hearns, Milton McCrory and Roger Mayweather, with the latter two being a poor man's version of the first.
Hearns, McCrory, Hilmer Kenty, and Jimmy Paul all had the similar Kronk style. But obviously... Hearns was lightyears ahead of the other 3.
Best bet is to stick ot the standup stylists and textbook boxer types.Buchanan, Winstone, Famechon, Kingpetch, Giardello etc.. Jim McDonell was kind of like a B level fighter version of him, but he's not in the class of any of the other fighters you could watch above.