What is "ur-du-kuga"

Ur-dukuga, written ur-du-kù-ga, ca. 1767 BC – 1764 BC ( short chronology) or ca. 1830–1828 BC ( middle chronology), was the 13th king of the 1st dynasty of Isin and reigned for 4 years according to the Sumerian King List, 3 years according to the Ur-Isin kinglist. He was the third in a sequence of short reigning monarchs whose filiation was unknown and whose power extended over a small region encompassing little more than the city of Isin and its neighbor Nippur. He was probably a contemporary of Warad-Sîn of Larsa and Apil-Sîn of Babylon.