Conflict in leaving certificate and adhaar

Hello, My uncle is 62yr old. He have all his documents (adhaar card, pan card) all these years as dob 01-06-1956... But recently, for ECR status of passport, he went to get his leaving certificate and found out that his leaving certificate have dob 01-06-1955. He submitted his adhar, pan and leaving certificate for passport, and by mistake filled form as 01-06-1955 as per leaving certificate instead of 01-06-1956 as per adhaar and pan card. And he got passport as dob 01-06-1955.. Now he wants to change it. Kindly advise on the procedure... And if it is possible or not??