Harlequin published 477 titles between 1949 and 1959 while Export published 165. The second and last shared title is William Hopson's Hell's Horseman, originally published by Phoenix Press of New York in 1946. The shared back cover blurb is likely from this edition.
News Stand Library 126 - August 1950
News Stand Library 126 back
Harlequin 275 - February 1954
Harlequin 275 back