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To find the second occurrence of “Mango” in column A and get the corresponding value from column B, you can use the following QUERY formula:
=QUERY(A1:B, "SELECT B WHERE A='Mango' LIMIT 1 OFFSET 1", 0)
If your data has a header row, you should use it as follows:
=QUERY(A1:B, "SELECT B WHERE A='Mango' LIMIT 1 OFFSET 1 LABEL B'' ", 1)