The Colonials (6-4, 5-0 Northeast Conference) used George Martin's 2-yard TD run in the first quarter, and Martin's 7-yard scoring toss to Tim Vecchio and two Nick Bisceglia field goals in the second quarter to take a 20-0 lead into halftime.
The Dukes (6-3, 4-1) got on the scoreboard early in the third quarter when Brett Brumbaugh hooked up with Dominic Thieman for a 13-yard TD, but on Duquesne's next series Gray picked off Brumbaugh and turned it into a 36-yard score for a 27-7 Colonials' lead.
Duquesne cut its deficit to 27-14 on A.J. Hines' 1-yard TD run, but Gray picked off Brumbaugh again on the Dukes' next series and raced 81 yards for a score and a 34-14 lead with 3:36 remaining in the game.
Brumbaugh hit Kellon Taylor for a 22-yard score to get the Dukes within 34-21 with 2:29 to go, but Terence Stephens Jr. raced 47 yards for a Colonials' score on first down to put the game away.
Stephens finished with 119 yards rushing on 20 carries for Robert Morris.
Brumbaugh completed 24 of 50 passes for 302 yards and two scores, but he threw four picks. Taylor finished with six catches for 113 yards and a score, while Kareem Coles Jr. hauled in 10 passes for 100 yards.
Robert Morris remained tied with Central Connecticut atop the NEC, while Duquesne fell a game off the pace.
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