The ktpass command structure for additional Teradata Vantage nodes, is similar to the structure for the first node, except for the added -in parameter, for example:
ktpass -princ SPN -mapuser node_name -pass password -ptype KRB5_NT_PRINCIPAL -out keytab_filename -in keytab_filename
where the value for the -in parameter is the same keytab filename you specify for the -out parameter. See the description in Generating the Key for the First Node or for a Unity Server.