In the early days Harlequin was a reprint publisher but did publish a few original books. The first one, The House on Craig Street by Ronald J. Cooke (#7), can be seen on one of the address books. Cooke was a Canadian business writer and editor who had another Harlequin novel - The Mayor of Cote St. Paul (#56).
The House on Craig Street was reprinted by Harlequin but then, uniquely, was also published in November 1949 by another Canadian paperback publisher - Export Publishing Enterprises as News Stand Library #11A. The cover states "sold out first printing" but since there was only one printing of Export's edition the blurb must refer to the Harlequin edition. Why the new edition?
Export sold its books in Canada. But they did create a second series of 28 books for distribution in the US. This series had an "A" after the number. The Export edition of House was one of these books. Harlequin, as a new publisher, likely did not have a distributor in the US and either Harlequin or the author contracted with Export to produce an edition for sale in the US - trying to capitalize on its success in Canada. The back cover blurb on both books is identical.
The Export covers are below. Interestingly the front cover is a different rendering of the same scene by the same artist (D. Rickard) who did the Harlequin cover. Also below is an inscription by the author in a copy of the Harlequin edition.