SELECT ax.str ,
  b.str
FROM
  (SELECT v.person_id,
    v.date_day,
    v.str
  FROM V_EXPORT_GROUPS_VALENS_2020_2 v ,
    GU_PERSON GP
  WHERE v.PERSON_ID =GP.PERSON_ID
  AND GP.GUI_USER_ID= 101952
  AND date_day     >= TO_DATE('01/05/2020', 'dd/MM/yyyy' )
  ) ax,
  (SELECT v.person_id,
    v.date_day,
    v.str
  FROM V_EXPORT_GROUPS_VALENS_2020 v ,
    GU_PERSON GP
  WHERE v.PERSON_ID =GP.PERSON_ID
  AND GP.GUI_USER_ID= 101952
  AND date_day     >= TO_DATE('01/05/2020', 'dd/MM/yyyy' )
  ) b
WHERE ax.person_id = b.person_id (+)
AND ax.date_day    = b.date_day;