1)
This is verse 4. Why is it repeated?
1.
Radak: After You will judge the nations that will come with Gog and Magog, the other nations will thank You and know that You alone are supreme above the entire land. "Amim Kulam" includes those who will escape alive from the camp of Gog and Magog - "v'Samti Vahem Os" (Yeshayah 66:19).
2.
Malbim: Now they request that rain descend for Brachah. From the withholding of rain it became known that Hashem judges straightly. After He was appeased with the land, they will thank Him for the good.