Andre Bikey will serve the first game of his three-match suspension following his dismissal in the 2-2 draw at Cardiff last time out, with Duberry set to deputise.
The Royals could also opt for Kalifa Cisse in defence, but Coppell told the club's official website: "I will more than likely start with Doobs because he is a specialist in the position."
Captain Graeme Murty featured for 60 minutes in the reserve friendly against Exeter and is getting closer to a first-team return.
Defender Sam Sodje remains doubtful with a knee injury, while striker Dave Mooney is also unlikely to be involved with an ankle injury which has kept him on the sidelines recently.
Coventry manager Chris Coleman is set to be without defenders Stephen Wright and Isaac Osbourne.
Wright went off with damage to his medial ligaments after just 33 minutes of their 1-1 draw at Swansea last time out and his replacement Isaac Osbourne only lasted 12 minutes after being forced off with an ankle problem.
Wright looks set to be out for 10 days to two weeks, while Osbourne faces a longer layoff of up to three months.
Midfielder Jay Tabb was back in training on Friday after missing two games with a virus and Coleman revealed he is expected to be fit enough to make the Sky Blues squad for the match at the Madjeski Stadium.