Damon attended Auburn University in Auburn, Alabama, where he played for the Auburn Tigers football team from 1999 to 2002. He is considered one of the best kickers and punters in Auburn football history. During his college career, Duval amassed over 9,000 punting yards for an average of 44 yards per punt. His 60.8 percent field goal completion rate helped Auburn to a 29-19 record during his four seasons with the team, including appearances in the 2000 Citrus Bowl and 2001 Peach Bowl. Memorably, Duval kicked a 44-yard game-winning field goal in the rain against the No. 1 ranked Florida Gators with 10 seconds left in the game in 2001. It was one of three game-winning field goals he made for the Tigers in 2001.
Despite being one of the top kickers available in the 2003 NFL Draft, Duval was not drafted into the National Football League, but did sign as an undrafted free agent with the NFL's Jacksonville Jaguars. He was waived by Jacksonville on June 19, 2003 and later signed with the Atlanta Falcons. He was waived by Atlanta on August 29, 2004, and subsequently left the NFL to sign with the Montreal Alouettes of the Canadian Football League. Duval made an immediate impact in the CFL, leading the league in scoring his rookie season (2005) with 191 points and proved to be very reliable kicking field goals. His 2005 CFL highlight came in the 93rd Grey Cup when he made a 27 yard field goal with no time left to force overtime. Continuing his 2005 success, Duval led the league in field goal percentage with 86.4% in 2006 which led to his making the 2006 All Star team. He also finished second in kicking points (201), punting average (45.4 yards) and kickoff average (61.1 yards). Duval's strong play helped Montreal reach the 94th Grey Cup by kicking a game sealing field goal in the Division finals. Unfortunately, his team fell short again despite Duval's 43 yard field goal in the second quarter. On November 7, 2009 he set the record for points in the CFL regular season with 242, again with the Montreal Alouettes.
In the 2009 Grey Cup Championship November 29, Duval's field goal from 33 yards out on the game's final play gave the Alouettes a 28-27 win over the Saskatchewan Roughriders, capping a remarkable Montreal comeback. Duval had actually missed a 43-yard field goal attempt on what should have been the last play of the game, but the Roughriders were penalized for having too many men on the field. Duval helped the Alouettes win back-to-back Grey Cups with the team's second straight win in 2010.