Some 15% of the 477 titles Harlequin Books published between 1949 and 1959 were changed for their edition. The publisher with the most changed titles is Mills & Boon - 20 of the 50 that Harlequin reprinted in that period. Unlike Harlequin's other title changes the Mills & Boon ones were noted on the copyright page. Here are two.
Hospital In Sudan first published as Doctor Immacula (1958) To Please the Doctor first published as Borne on the Wind (1950)