A.D. Amorosi To hear Tony Bennett’s son and longtime manager Danny Bennett tell it, a friendship ensued between his standard-bearing father and the mod-pop chanteuse Lady Gaga after their first duets album, 2014’s platinum-plated “Cheek to Cheek.” The pals always came back to Tony’s “Cole Porter Medley,” from 1975, as the gold standard of American song and the model for a next collaboration.