Mysql grouping problem inside a Trigger

Question

I have the following Rigger code, where it makes a select on the main tables (DADF311, DADF313.. ) to insert the result ready in the secondary table (DADF514):

DELIMITER $$
CREATE TRIGGER ta_dadf311 AFTER INSERT ON dadf311 FOR EACH ROW 
BEGIN
DELETE FROM dadf514 WHERE datreg = NEW.datreg;

INSERT INTO dadf514(datreg, codreg, nomreg, totnot, quanti)
SELECT DATE_FORMAT(dadf311.datreg, '%Y%m') AS datreg, dadf311.codreg AS  codreg, 
(CASE WHEN dadf311.nomreg IS NULL THEN 'SEM REGIÃO' ELSE dadf311.nomreg END) AS nomreg, 
SUM(dadf313.valtot + dadf313.valfre) AS totnot,
SUM(dadf313.quanti) AS quanti
FROM dadf311
LEFT JOIN dadf313 ON (dadf311.tipnot = dadf313.tipnot) AND (dadf311.numnot = dadf313.numnot)
LEFT JOIN dadf016 ON (dadf311.natope = dadf016.codigo)
WHERE 
  dadf311.tipnot = 'NS' AND
dadf311.para01 = '00' AND
DATE_FORMAT(dadf311.datreg, '%Y%m') = DATE_FORMAT(NEW.datreg, '%Y%m') AND
dadf016.para10 = '01' 
GROUP BY DATE_FORMAT(dadf311.datreg, '%Y%m'), dadf311.codreg;

END;$$

DELIMITER ;

The problem is in the grouping, where should insert ANOMES with their respective values, my result is repeating as example below:

datreg  codreg  nomreg            totnot     quanti  
------  ------  -----------  -----------  -----------
201712       0  SEM REGIÃO     3670.0000       2.0000
201712       0  SEM REGIÃO     4979.2300      53.0000
201712       0  SEM REGIÃO     7239.1300      59.0000
201712       0  SEM REGIÃO     7239.1300      59.0000
201712       0  SEM REGIÃO    10909.1300      61.0000
201712       0  SEM REGIÃO    14579.1300      63.0000
201712       0  SEM REGIÃO    15751.8700      78.0000

One detail that may be causing this, would be the DATREG field of the DADF514 table, it is of type INT, and the DATREG field of the DADF311 table is DATETIME