POSTGRESQL - функция UNNEST не работает в LINUX

Question

Я получил дубликат строки. хотя я уже добавил "DISTINCT", когда я запускаю запрос дубликаты записей показывают.

    id | product | service
    ---+-----------------------
    1  |p1       |s1
    2  |p2       |s2
    3  |p2       |s2

  SELECT DISTINCT billing_billmanagement.creation_date,
                            billing_billmanagement.bill_number, 
                            unnest(array_agg(DISTINCT inventory_product.product_name)) AS product,
                            unnest(array_agg(DISTINCT services_service.name)) AS service
            FROM billing_billmanagement
            INNER JOIN users_staffuser ON (billing_billmanagement.staff_id = users_staffuser.id)
            INNER JOIN auth_user ON (users_staffuser.user_id = auth_user.id)
            LEFT OUTER JOIN billing_customerproductbill ON (billing_billmanagement.id = billing_customerproductbill.bill_id)
            LEFT OUTER JOIN inventory_product ON (billing_customerproductbill.product_id = inventory_product.id)
            LEFT OUTER JOIN billing_customerservicebill ON (billing_billmanagement.id = billing_customerservicebill.bill_id)
            LEFT OUTER JOIN services_service ON (billing_customerservicebill.service_id = services_service.id)
            LEFT OUTER JOIN billing_customer ON (billing_billmanagement.customer_id = billing_customer.id)
            WHERE billing_billmanagement.creation_date BETWEEN '2017-11-01' AND '2017-12-02'
            GROUP BY billing_billmanagement.creation_date,
                     billing_billmanagement.bill_number
            ORDER BY billing_billmanagement.creation_date ASC

Что-то здесь не так?