Duke was selected in the first round of the 2013 supplemental draft out of the University of San Diego. The native of Overland Park, Kan., played for the Sporting KC Academy before helping lead San Diego to the NCAA tournament as a senior.
He made eight appearances for Sporting KC in preseason matches.
Jerome played the past two seasons for the club's USL PRO affiliate, Orlando City SC. The native of Haiti has been on trial with Sporting KC this preseason, and scored the only goal in an exhibition victory against Portland.
Sporting KC opens the regular season Saturday at Philadelphia.