Duffy, 19, has made two first-team appearances for the Toffees - both coming in the 2009/10 Europa League when he came off the bench in the 1-0 win at AEK Athens then started in the home loss to BATE Borisov by the same scoreline.
Those games both came in December 2009, but he has not featured in boss David Moyes' senior plans since then and played one game on loan for Burnley in the Championship last season.