Demand pais twice to income tax department.

My brother filed his income tax return for AY 2016-17 in March 2018. While filing the return he paid self assesment tax of Rs 7240/-. But he forget to mention in ITR-I relevent column. His Income Tax Return processed with a demand raised U/S 245 of same amount ₹7240/- in month of Apr 18. He noticed about this demand in the month of Aug 18 and he thought that it is his mistake so he again paid the ₹ 7240/- as assesment tax as demanded by IT dept. He discussed this matter to me and I advised him to file rectification request. He did same and now his return is rectified. But now he paid extra ₹ 7240/- to income tax department. How to get this amount back.