Amidst its description of Yaakov's resettlement in Egypt, Parashat Vayigash digresses to list the names of Yaakov's children and grandchildren who joined him. This list includes the lone son of Dan (the eldest son of Bilha), Chushim. Curiously, however, the Torah employs the plural form, as if Dan had more children than just Chushim: "U-vnei Dan Chushim" (literally, "The sons of Dan: Chushim"). The Gemara in Masekhet Bava Batra (143b) cites this verse in an attempt to decide a case involving a father of a son and daughter who declares that he bequeaths his possessions "le-banai" - "to my sons." Does he refer to his son or to both children? This question hinges around the issue as to whether a single son can be referred to with the plural form "banai." Abayei cites our verse as evidence that indeed the plural form can refer to just a single son. Rava, however, dismisses the proof, citing a different explanation for the Torah's use of the plural form in our verse. The Torah here may have meant that Dan's descendants were numerous like "chushim," or reeds. The Gemara then brings other instances in Tanach where the word "u-vnei" appears in reference to a single son.
What emerges, then, are two different explanations for the plural form "u-vnei" in this verse: either this term can, at times, refer to a single son, or it alludes to the multitude that emerged from Chusham's offspring.
The Ibn Ezra, however, suggests that Dan had two sons, one of whom died. The plural form is used include the other son as part of Dan's family. Now since the verse reads, "Dan's sons: Chushim," the Ibn Ezra presumably claims that Dan had two sons named Chushim. As it is hardly likely that Dan would give the same name to both his sons, we may assume that, according to the Ibn Ezra, Dan's second son waborn after the death of his first, and he named his second son, Chushim, after his first son who bore that name.
Interestingly enough, Rav Aharon Levin, in his "Ha-derash Ve-ha'iyun," notes a possible halakhic ramification of the Ibn Ezra's position. Rav Levin cites earlier sources who discuss the propriety of naming a child after an older sibling who had died, and notes that at least according to the Ibn Ezra's interpretation, we have proof that indeed one may do so.