Kommentar zu Bereschit 46:21

בלע ובכר, we must not make an issue of the number of Binyamin’s sons, as according to the report in Chronicles I 8,15 there were 11 sons. We must simply assume that at the time when Binyamin descended to Egypt the eleventh son had not yet been born. The difference in some of their names may also be accounted as due to their being listed once more. This is something we find also in other instances where the Bible records the same people more than once.

וארד, the letter ו in this word is vocalised with the vowel kametz.