Q. How come there are two Books of Kings in the Bible, not one?
One view is that these divisions did not derive from Jewish but Christian sources, largely Archbishop Stephen Langton in the early 13th century.
If you add up the Books in the English Bible you find more than the Jewish enumeration of 24, because Christians did not follow the Jewish traditions of where and when sections of the Bible began and ended.
When Jews adopted the Christian enumeration it was not because they believed in it but for ease of reference in disputations with Christians. The latter would cite a chapter and verse and Jewish respondents needed to identify the text quickly.
However, there are earlier Jewish traditions such as the Septuagint that separate Samuel I and II and Kings I and II.
In regard to the Torah, the Christian influence was responsible for dividing the texts into chapters even when Jewish usage saw no need for particular divisions. An example is the verses that Christianity chose for the commencement of Gen. 2. These verses, narrating the end of the seven days of creation and the institution of the Sabbath, more logically belong to the end of Gen. 1.