Question On The Old Mortgage

My Maternal Grandfather had mortgaged a house twice back in 1980s and repaid the loan and got back the documents. But As we see now both was not receipt registered. The last one we receipted now by approaching the bank while asking them why it was not receipted the bank told us back in that time we receipt only on request. the other mortgage we can't find the canceled document which we are searching now. Any idea how this worked before and is there a problem because of this?