What a relief to have finally determined the cause of those "duplicate entries" for Mary Frances, daughter of Thomas and Elizabeth Gordon. It is always worth it to backtrack and double check all the supporting documentation for each entry in a family tree—particularly keeping in mind that sometimes, even the documents themselves can lead us astray.
One lesson from this foray into my genealogical spring cleaning project was that, especially in the case of family members with similar or exact same names, it is best to confirm information with more than one document. If I had looked for a second document confirming Mary Frances' mother as Elizabeth McCann, I would have been hard pressed to proceed. I would have been more likely to find a multiplicity of documents confirming that mother's maiden name to be Elizabeth McCabe.
It also helps to look to other resources, as well. Granted, there aren't really many other reliable sources besides governmental or church records, but in some cases, family members who are closer to the person being researched can be helpful. (Or not; people sometimes have the worst memory for details seemingly closest to them.) That said, Mary Frances was my mother-in-law's second cousin once removed, so not likely someone she knew personally; that option was not open to me in this case.
Another resource I like to double check is the local newspaper. Yet, once again, I of all people have constantly bemoaned the inaccuracy of some editorial oversight. But really, all we can ask for is the gathering together of several different documents and sources which, each in their own right, are nothing more than records composed by fallible people. Much better to assume that is the truth of the matter, and put your reliance on a multiplicity of reports.
It wasn't hard to see, for instance, in the one September 30, 1963, report bearing her name in the Zanesville, Ohio, Times Recorder, that Mary Frances' mother's name was Elizabeth McCabe. It said so, right in her obituary.
Mrs. Mary Frances Hennessey, 79, of 445 Van Horn avenue died at her home at 2:10 a.m. Sunday after an illness of six months. Mrs. Hennessey was a native of Perry County and was born April 13, 1884, a daughter of Thomas and Elizabeth McCabe Gordon. She had lived in Zanesville the past 23 years.
Adding this to the other documents we've already located combines to create a convincing case that the clerk of the probate court in Perry County got that maiden name wrong, when Mary Frances and John Patrick Hennessy filed for their marriage license back in September, 1912.
And so, here I am, freshly supplied with an updated (and more reassuring) collection of supporting records—on the theory of genealogical safety in numbers—ready to reassess the situation of my "duplicate" entry in my mother-in-law's family tree. But not so fast, here: I can't simply delete the other Mary Frances Gordon, the one who turned out to be a duplicate, after all.
Before I return to my genealogical spring cleaning errands and begin a wholesale deletion of that Mary Frances, supposed daughter of Elizabeth McCann, I have to rescue all the details associated with that file. You see, I have descendants for that family down to the level of her grandchildren, tied into that entry. If I delete that Mary Frances, I lose all the records associated with her from that errant side of the family.
First, I have to go back, cross check each child's file—and their spouses and children, as well—to make sure I've transferred all the correct information to the new record established under Elizabeth McCabe's daughter Mary Frances. For, you see, as luck would have it, the Mary Frances originally residing under the correct mother was the one for which I hadn't made any progress at all. It was the false Mary Frances whose file contained all the family goods.
Above: Excerpt from the obituary of Mary Frances Gordon Hennessey in the Zanesville, Ohio, Times Recorder, Monday, September 30, 1963, courtesy Ancestry.com.