regarding land purchased.

my father purchased a land 18 yrs back from his friend. while checking encumbrance certificate now, I found now that my father's friend had taken loan from Co operative bank 30 yrs back and mortgaged the land that we had purchased . That loan amount has been waived off by the govt. but the change of ownership from the bank has not been transfered back to my father's friend.later on, without checking the documents,my father purchased a land that time. will it be a problem in future? if yes, how to correct it?