Another good catch, Deborah. The MacMoroughs were fond of reusing certain given names, but the book clearly states:
113. Diarmuid - na - nGall ("na- nGail:" Irish, of the foreigners): the elder son of Donoch MacMorough; was the 58th Christian King of Leinster; is known as "Dermod MacMorough;" became King of Leinster in 1135; was in 1166 deposed by the Monarch Roderick O'Connor, aided by Tiernan O'Ruarc, Prince of West Brefni; d. in Ferns in January, 1171. Dermod MacMorough had:
I. Aife (or Eva), who was m. to Richard de Clare, known as "Strongbow" she d. in 1177.
II. Art, slain in 1170 at Athlone, by the Monarch Roderick O'Connor, to whom said Art was given as a hostage.
III. Donal Caomhanach, a quo O'Kavanagh. (See the "Kavanagh" pedigree.)
IV. Eanna Ceannsalach, a quo O'Kinsela. (See the "Kinsela" pedigree.)
V. Orlacan, who m. Donal Mor, No. 110 on the "O'Brien" (No. 1) pedigree.
https://archive.org/details/irishpedigreesor011915ohar/page/556/mod...
The Geni father given to this particular Leinster King is actually his uncle, as apparently no profile exists of his father. Of his father the book states quite clearly:
112. Donoch MacMorough: the third son of Murcha, No. 111, was King of Dublin, and the 56th Christian King of Leinster; slain in 1115 by Donal O'Brien and the Danes at Dublin. He had two sons:
I. Diarmuid-na-nGhall, of whom presently.
II. Murcha* (or Moroch)-na nGaodhail, from whom descended Davidson or MacDavy Mor. This Murcha was in 1166 elected successor to his brother as King of Leinster, when Diarmuid-na nGhall was deposed.
FOOTNOTES: * Murcha: We have seen it stated in a Genealogical Chart in one of the Kilkenny Arch. Journals, that the Clan-Morochoe descended and derived their name from this Murcha; but MacFirbis distinctly states that the Clan-Morochoe is descended and takes its name from Murcha who is No. 111 on this [the John O'Hart] pedigree.
** MacMorough: In 1153 Dermod MacMorough carried off Dearvolga, daughter of O'Melaghlin, the last King of Meath, and the wife of O'Ruark, Prince of Brefney. On this subject Webb writes: "The transaction cannot have had much of the romance usually associated with the idea of an elopement. She was forty-four years of age, and did not leave her lord without carrying off her cattle and furniture. This was fifteen years before Dermot sought Anglo-Norman assistance; so that the invasion (of Ireland) can scarcely be attributable to the elopement.....Dearvorgal spent much of her later life in religious exercises, and part of her substance in endowing churches. She survived until 1193, when she died at Mellifont Abbey, county of Meath, which she bad enriched with many presents. Although Dermot's Kingdom nominally passed into Earl Strongbow's family after his decease, much of it appears to have been soon again occupied by the MacMurroughs, by whom it was held in almost undisputed sway for several centuries."