Wherever any deed of conveyance registered prior to January 1, 1886, purports to have been attested by two witnesses and in the certificate of probate and acknowledgment it is stated that the execution of such deed was proven by the oath and examination of one of the grantors in said deed instead of either of the witnesses named, all such probates and certificates are hereby validated and confirmed, and any such deed shall be taken and considered as duly acknowledged and probated. (1925, c. 84.)