Peters, 24, played in three games last season after being promoted to the 53-player roster on December 12. Washington first signed him to the practice squad on November 13.
He began his NFL career with the Seahawks, but they waived him at the end of the preseason.
Stewart, 24, signed with the Broncos as an undrafted free agent last May. Denver cut him out of the preseason.
He spent a month on the Bills’ practice squad before they cut him, and he joined Washington’s practice squad on November 15.
Stewart, a Baylor product, has yet to play an NFL game.