James/Jacob is even messier! They come from the same name, but are in English treated as completely distinct names. In the New Testament Greek, you get Ἰακώβ (iakob) used for Old-Testament-era Jacobs (primarily the one later given the name Israel, but also the one in Matthew 1:15–16), and Ἰάκωβος (iakobus) used for New-Testament-era Jameses (two of Jesus’ disciples, and one of his brothers). English Bibles have ended up using Jacob for the old and James for the new ones, but not all languages maintain the distinction: in Telugu, for example, they’re all యాకోబు (yakobu).
https://en.wikipedia.org/wiki/James_(given_name)
https://en.wikipedia.org/wiki/Jacob_(name)