In the ring... Mayweather is like the Spurs of the NBA. Horrible to watch, boring and predictable, but works very efficiently within the rules and just keeps the opponent from scoring.
The 2nd fight would look just like the first fight. Sure, we'd all love to see Mayweather with a busted lip, but let's face it, at this age, these guys can't hit hard anymore. Floyd admitted his hands are weakened for fighting, and that's why he hasn't had a KO in 5 years now. The 2nd fight would look just like fight #1.