Penny and Guerrero were involved in a benches-clearing brawl on March 10 after the Marlins' starter beaned the Expos' slugger. Penny was hit with a five-game suspension, Guerrero was suspended three games and Montreal infielder Jose Macias, who joined the altercation, was hit with a two-game ban.
Tuesday, Dupuy upheld Penny's sentence, which is set to begin March 31. Guerrero agreed to drop his appeal and in turn had his suspension reduced to two games. He will begin serving his suspension March 31.
"I'm glad that (the suspension) is two games instead of three games," Montreal General Manager Omar Minaya told MLB.com, the official Web site of Major League Baseball. "I wasn't surprised (that it was reduced). It happens a lot of times. If you look at the history of the cases, there are a lot of times these suspensions get reduced one game."
"He's going to miss two ballgames and we will have to go on," Manager Frank Robinson told the Web site.
Macias was seen hitting Marlins catcher Matt Treanor in the melee. He also did not appeal his two-game suspension, which is scheduled to start April 4.
All three players were fined.
DuPuy also reduced the sentence handed down to Los Angeles' Guillermo Mota, who was involved in a brawl with the New York Mets' Mike Piazza on March 12. Mota initially was suspended five games but had his sentence reduced to four games Tuesday.
Piazza appealed his five-game ban.