His death certificate records James B. Duff, age 89 years 8 monts 15 days, born 29 Nov 1824 in Berthshire, Scotland, died 14 Sep 1914 in Franklin township, Grundy Co., Missouri, married, father William Duff, mother’s maiden name Jean Watt, both born in Scotland, cause of death traumatic peritonitis following an injury from a fall, informant May Shelton, Spickard, Mo, burial in Masonic.

I cannot find any place in Scotland called Berthshire. It may mean Perthshire.

Her death certificate records Mary Ann Duff, age 84 years 5 months 21 days, born 3 Apr 1843 in Covington, Ky, died 24 Sep 1927 in Marion township, Grundy Co,. Missouri, widowed, father Wm Brown, mother’s maiden name Anna Fowler, both bornin Ky, cause of death myocarditis, informant Mrs. Byrl Shelton, Galt, Mo, burial in Spickard.

Daviess Co., Missouri marriage records list the marriage on 4 Apr 1884 of Mr. James B. Duff, age 59, and Mrs. Mary A. Babb, age 40, both residents of Grundy Co., Missouri, by J. A. Selby, J.P.

1900 census of Grundy Co., Missouri, Franklin township, Spickardville, enumerated 2 June, lists on p. 2B as family #53:
Duff, Jas B., 75, b. Nov 1824, Scotland Scotland Scotland, immigrated 1859, naturalized citizen, farmer, married 50 years; Mary A., wife, 57, b. Apr 1843, married 39 years, mother of 9 children, 7 living, b. Ky Ky Ky; Babb, Bertha L., stepdau, 20, b. Feb 1880, Missouri Tennessee Ky.

They have apparently both interpreted the number of years married to be the number of years since their first marriage.