Currently contracted until the end of the 2010 season, Duffield, 24, has agreed to a contract extension taking him through to the end of the following year.
Schammer, 24, who is contracted until the end of 2009, has agreed to terms taking him through to the end of 2011.
General manager of player management Brad Lloyd said today that Duffield and Schammer were important to the future direction of the club.
“When you consider that we have had 11 players make their AFL debuts this season, Paul and Byron, who are both 24, help maintain the right blend of age and experience in our list management model,” he said.
“Paul has had a breakout season in defence and Byron has probably had his most consistent season since arriving at Fremantle.”
