Is this Kalev ben Chetzron?
'Rashi': Yes. He is called ben Yefuneh, for he was Mefaneh (cleared) himself from the Meraglim's counsel (Sotah 11b). Even though the family of Kalev ben Chetzron was already taught, the Sefer often teaches lineage, digresses, and returns to the first family.
Below, it teaches the names of Kalev's wives. From whom were these sons?
Malbim: He had four wives. These sons are from his first wife; her name was not mentioned.
Why does it say "u'Vnei Elah u'Kenaz"?
'Rashi', Radak: His name was u'Kenaz. Malbim - we find that an initial Vov can be part of a name (refer to 2:18:2:4). Only one son is listed here; Ezra copied u'Vnei from the great Sefer of lineage, which listed also others.
