Haggai 1

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> [1]In the second year of Darius the king, on the first day of the sixth month, the word of the Lord came by the prophet Haggai to Zerubbabel the son of Shealtiel, governor of Judah, and to Joshua the son of Jehozadak, the high priest, saying,
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Daniel 5:29-31

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> [29]Then Belshazzar gave orders, and they clothed Daniel with purple and put a necklace of gold around his neck, and issued a proclamation concerning him that he now had authority as the third ruler in the kingdom.
>  [30]That same night Belshazzar the Chaldean king was slain.
>  [31]So Darius the Mede received the kingdom at about the age of sixty-two.
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According to the (Bible Timeline)the 2nd year of Darius reign was around 538BC in Daniel 5,but in Haggai 1 the 2nd year of Darius reign was around 520BC.

How can we reconcile this supposed contradiction?