On June 6, Lopez had tested positive for a banned substance - Formestane, an estrogen-control agent that reduces helps build lean muscle and strength - so he was suspended for 50 games.
Duncan, who helped St. Louis Cardinals win the 2006 World Series, left Syracuse July 27 to deal with undisclosed medical issues, according to Doug Harris, the Washington Nationals' director of player development.
Chiefs v. Yankees Aug. 21-22
The Syracuse Chiefs play the IL West division-leaders, the Columbus Clippers, at Alliance Bank Stadium at 7 p.m. Wednesday and Thursday, Aug. 11-12, before hitting the road to Indianapolis and Louisville through Aug. 20.
On Aug. 21 and 22 the Scranton/Wilkes-Barre Yankees return to ABS for a two-game series with games at 7 p.m. Saturday and 5 p.m. Sunday, Aug. 12.
ABS is located on the city's North Side, on Tex Simone Drive, just east of the Regional Market. Tickets cost $11 for field-level seats, $8 for kids and seniors; $8 for second-tier seats, $4 for kids and seniors; and parking costs $4 per vehicle; 474-7833; syracusechiefs.com.