Adam Clarke on 1 Chronicles 3:1

The second, Daniel - In 2Sam 3:3, this person is called Chileab; he probably had two names. The Targum says, "The second, Daniel, who was also called Chileab, because he was in every respect like to his father." The Targumist refers here to the import of the word כלאב ke-le-ab, like to the father. Jarchi says the two names were given to this person because David, having taken Abigail immediately after the death of Nabal, it could not be ascertained whether this child were the son of David or of Nabal, therefore David called him דניאל Daniel, God is my Judge, and כלאב Chileab, he who is like to the father; probably from the striking resemblance he bore to David, his reputed father. "God is my Judge, I have not fathered another man's child; this is entirely like unto myself.