Lukaku left United last summer for the Nerazzurri while former captain Young departed in January.
Inter's accounts showed Lukaku joined Inter last summer for a fee believed to be £73.9m, however Inter's accounts show the Italian side in fact paid €74.162 - around £66.75m.
United were holding out for £80m for Lukaku as they were reluctant to take a hit on the £75m they paid Everton for him in 2017.
Ashley Young left United for Inter in January and cost precisely €1.729m (£1.55m). United communicated at the time they had received €1.5m, plus some add-ons.