We depend upon records to reveal the “truth” about the past. Yet sometimes records have anomalies. Some are amusing or humorous. Some are interesting or weird. Some are peculiar or suspicious. Some are infuriating, or downright laughable.
Records are the darnedest things!
(This article is based an Larry Martin’s winning entry to my RootsTech 2016 contest. Congratulations, Larry!)
Josephine Demerris Duffy is Larry’s wife’s late mother who has a darned confusing birth. She and her family always celebrated her birthday on May 17th. But birth records disagree as to the date and place of the birth.
Chicago, Cook County recorded her birth as 17 June 1912, on East Oak Street in Chicago, of Irish parents.

Josephine Demerris Duffy birth certificate1
According to published abstracts, Cook County recorded her birth a second time, specifying the same date and parents, but with a different birthplace and ethnicity: Cullom and Canadian.

Josephine D Duffy birth record on Ancestry.com2
There is no town named Cullom in Cook County but there is a Cullom Avenue in Chicago. The 1910 Census shows Josephine’s parents lived on East Oak Street (above their grocery store), however, and not on Cullom Avenue.

John Duffy in 1910 United States Census3
Like any good genealogist, Larry used the Ancestry.com database as a finding aid. He has ordered the cited microfilm. When it arrives he will see this:

Josephine D Duffy in birth register4
It is apparent the indexer took “Cullom Avenue” from the wrong line, but where he got “Canadian” from is anyone’s guess. The information in the register matches the certificate. I haven’t shown enough to see, but all surnames on the page start with the letter D and the entries are not strictly chronological. While the opposite page contains additional information, the certificate contains even more.
The Holy Name Cathedral, Chicago, recorded her baptism of 2 June 1912, noting her birthdate as 17 May 1912, with her parents listed properly.

Josephine Duffy in baptismal register5
The baptismal dates are in strict chronological order for several pages before and after this page.
What do you think? When was Josephine born?
Yes, records are the darnedest things!
Sources
1. Cook County, Illinois, birth certificate no. 3659 (1912), Josephine Demerris Duffy, County Clerk, Chicago; FHL microfilm 1,288,245. Birth year is not specified, but determined by previous certificate.
2. Detail from screen image, “Cook County, Illinois, Birth Certificates Index, 1871-1922,” database, Ancestry (http://search.ancestry.com/cgi-bin/sse.dll?indiv=try&db=FSCookILBirth&h=2061451 : accessed 27 November 2015), Josephine D Duffy, 1912; from "Illinois, Cook County Birth Registers, 1871-1915," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:N7XY-4HV : accessed 27 November 2015); citing p. 75, no. 3659, County Clerk, Chicago; FHL microfilm 1,287,756.
3. Clips assembled from "United States Census, 1910," image, FamilySearch (https://familysearch.org/pal:/MM9.3.1/TH-1942-23041-3426-94 : accessed 26 November 2015), path: Illinois > Cook > Chicago Ward 21 > ED 913 > image 24 of 57; citing NARA microfilm publication T624 (Washington, D.C.: National Archives and Records Administration, n.d.). Don’t snip up your images in real life. It is a violation of Board for Certification of Genealogists, Genealogy Standards: 50th Anniversary Edition, Kindle Edition (Nashville, Tennessee: Ancestry.com, 2014), no. 28.
4. Clips from an image of Cook County, Illinois, “Apr – July 1912, Register of Births, A to Z,” 66:75, no. 3659, Josephine D Duffy, County Clerk, Chicago; FHL microfilm 1,287,756.
5. Holy Name Cathedral (Chicago, Illinois), baptisms, 1908-1915, Josephine Duffy, Holy Name Cathedral, Chicago; digital image,"Illinois, Chicago, Catholic Church Records, 1833-1925," FamilySearch (https://familysearch.org/pal:/MM9.3.1/TH-267-11395-27252-84 : accessed 27 November 2015), path: Holy Name Cathedral Parish (Chicago: State St) > Baptisms 1908-1915 > image 150 of 246; FHL microfilm 1,578,586.