One speculation is that this is more common in cultures that do not have surnames. In this case, Walter Kaiser in A History of Israel p.92, referring to the Ugaritic Textbook by Cyrus H. Gordon (1965), says the name Jethro (as well as Hobab) are found in the Ugaritic language.
Kuhusiana na baba mkwe wa Musa, Walter Kaiser kwenye A History of Israel uk.92, anataja Ugaritic Textbook cha Cyrus H. Gordon (1965) kama chanzo cha taarifa, anasema kuwa majina Yethro, (na Hobab) yapo kwenye lugha ya Kigariti (lugha iliyoongelewa maeneo ya kaskazini ya Siria ya kale).