The striker, 23, shook his head after he was found guilty of causing Sheffield United fan Reece Hall grievous bodily harm at Leeds Crown Court.
He was earlier found guilty of causing Wednesday fan Daniel Beresford actual bodily harm by a jury after a week-long trial and more than seven hours of deliberations.
Madine, who has a previous conviction for knocking a man out in a Carlisle pub, punched Mr Beresford in the Paris Bar in Sheffield city centre in February last year, breaking his nose.
Four weeks later, he punched bricklayer Mr Hall in the city's Viper Room club, shattering his cheekbone.
Judge Rodney Jameson QC gave Madine bail but told him: "You must understand that an immediate custodial sentence is very likely."
Judge Jameson told the jury of seven men and five women: "I agree with all of your verdicts. I think you've got it absolutely spot on."
The judge adjourned the case for sentencing so reports can be prepared. No sentencing date was fixed.