Dukes is recovering from a right calf strain, while Gonzalez is recovering from a left hamstring strain. Gonzalez likely will start his rehab assignment with Triple-A Columbus sometime next week, as he already is taking batting and fielding practice.
General manager Jim Bowden would not give a timetable for either player's return to Major League action.
In other news, catcher Jesus Flores will have a precautionary MRI on his right calf on Sunday. He hurt it on Saturday against the Rockies.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.