The Iron revealed last week that they had received an offer from Rovers for the 27-year-old, who has 12 months remaining on his contract at Glanford Park.
Scunthorpe boss Brian Laws said the bid was "way below" his valuation of the player.
Doncaster manager Paul Dickov has revealed that he has made another unsuccessful attempt to sign Duffy.
He told reporters at the club's training ground on Rovers' return to pre-season training: "He's a busy player who makes things happen and he has a bit of steel about him as well.
"But we have a valuation of the player and we won't be held to ransom, so that's now on the backburner."