This is not the first time that Paolo Di Canio’s side have been linked with Duncan, a 20-year-old Ghanaian midfielder.
He spent the last six months on loan at Livorno in Serie B and helped them to promotion via the play-offs.
According to Mediaset Premium, Sunderland are extending their negotiations to include 18-year-old defender Mbaye.
He was part of the senior Inter squad this season, but suffered from injury during the final few months of the campaign.
It is rumoured Black Cats representatives were in Italy on Friday to discuss the players with Inter.