Every boxer is diffrent. This being said. I think one voice in the corner is best. You only have :60 between rounds. If you have one guy saying one thing and another saying something else. The boxer who is going through the grind of a boxing match may be confused. If everyone is on the same page or has a spefic thing to look for and advise on it could work out to have more than one voice.
Saw it last weekend in Berto's corner. Horrible amatuer corner with very bad advice. The fighter hears nothing when two people are speaking over each other. One guy should control the corner, it should be agreed upon before the fight. If a second has advice he should tell the trainer during the round. Other than that one person should be speaking. The problem is the fighters make these stupid rules and allow their family members and others to be in the corner and the trainer doesnt want to speak up for fear of getting booted. I remember when one fighter, cant remember if it was Jermain Taylor or Vernon Forrest, allowed one trainer to speak for 30 seconds and then the other to speak for 30 seconds. Thats worthless too. Guys like Steward and Roach wont tolerate that stuff anymore.
I know right, it's like someone trying to give you advice while you are in the middle of a round of golf
Hagler's corner...the Petronelli's...always seemed to me to be an ideal corner...no shouting...always calm and in control..almost like they were whispering.