A kind correspondent (thanks Ken) has cleared up the mystery (at least for me) when Outlaw Deputy was first published. The answer is New York's Julian Messner in 1936 as Black Sheep as by Will F. Jenkins. It was first published under the new author name and title by Star Guidance, Inc. (New York, 1950) as Star Books 5.
Harlequin and Collins Canada had five sets of twins. The third one in this series of posts is Nurse's Aid by Lucy Agnes Hancock, first published by Macrae-Smith in 1943. The editions have the same text.
White Circle 295 - 1947
White Circle 295 back
Harlequin 356 - March 1956
Harlequin 356 back