For those not aware of the history of the character, the Golden Age Phantom Lady (Sandra Knight) was originally published by Quality Comics as a feature in Police Comics starting with issue #1 (cover-dated August 1941) and ending with issue #23 (cover-dated October 1943).
However, the character was not created by the people at Quality Comics.
Back in those days, quite a few comic book publishers would buy concepts / stories from other companies that specialized in creating and producing the comic book stories. (An early version of "outsourcing".) In the case of Phantom Lady, the feature was created by the Eisner & Iger Studio which was headed up by Will Eisner and Jerry Iger. (Later on Will Eisner left to focus on things like his weekly The Spirit Sunday comic strip section syndicated to newspapers.)
After Quality Comics stopped running the Phantom Lady feature, Jerry Iger eventually sold the feature to Victor Fox / Fox Feature Syndicate. (As to whether Iger's studio or Quality Comics really owned the rights to the character, who knows?) And the character Fox Feature published was essentially the same as the Quality Comics version, though the color of her costume changed and her outfit would become a tad more . . . revealing.
The Fox version of Phantom Lady first appeared in Phantom Lady #13 (August, 1947).
NOTE: There were no issues #1-12 with the title "Phantom Lady". The numbering continued from comic books with the titles of "Krazy Life" (#1), "Nuttylife" (#2), and "Wotalife Comics" (#3 - #12).
The "Phantom Lady" title ran from issues #13-#23, and then the book became "My Love Secret" with issue #24.
And in that first issue of Phantom Lady from Fox, there were two stories starring the title character:
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