1)
Here it lists Shamu'a and Elishu'a among David's sons. They are not listed above 3:1-8, and there it lists Shim'a, Nogah, and two sons each named Elishama and Elifelet!
1.
Radak (Shmuel II, 5:14, 15): Shamu'a is Shim'a 1 . Elishu'a is Elishama. Nogah and the other Elifelet are not listed here, for they died (Malbim ibid. citing Mahari - when they were minors); they are listed above, for it says "Kol Bnei David" (3:9).
1
Our texts of Radak say 'listed among Bnei ha'Pilagshim.' This is a printing mistake (refer to Shmuel II, 5:14:2:1).
