Was Zechariah Iddo's son or grandson?

Zechariah was Iddo's son.

Then the prophets, Haggai the prophet, and Zechariah the son of Iddo, prophesied unto the Jews. Ezra 5:1

Through the prophesying of Haggai the prophet and Zechariah the son of Iddo. Ezra 6:14

Zechariah was Iddo's grandson .

Came the word of the Lord unto Zechariah, the son of Berechiah, the son of Iddo. Zechariah 1:1