United took up a year’s option on Duffy’s contract this summer, but Laws has admitted Duffy could be ‘sacrificed’ to strengthen the side.
However Doncaster will have to increase their offer if they have any chance of landing the ginger winger.
“We’ve received an offer from Doncaster, which was well under the valuation which we are expecting,” he told the Scunthorpe Telegraph.
“We’re not in a position where we’re going to allow players to leave for next to nothing.
“We’ve paid money for him and we at least expect that back.
“No doubt about it, he had his best year since he’s been at the football club last season. He’s improved while he’s been there.
“And if someone improves you expect to get better money back.
“Doncaster’s valuation was way below ours.”
Sheffield United and Barnsley have also expressed an interest.