Fix query - JOIN duplicating rows

I have a query that retrives sales details from a list of tables.

When an invoice has 2 product lines with the same code (same product in DB), I get duplicated results.

I need somebody to fix the query to return unique values.

Query:

SELECT [url removed, login to view] ,[url removed, login to view], account_invoice.date_invoice,

[url removed, login to view],rep.litro_cantidad,

CASE WHEN rep.litro_cantidad > 0 THEN rep.monto_pesos / rep.litro_cantidad ELSE 0 END AS precio_venta,

rep.monto_pesos,

[url removed, login to view],

product_product.default_code

FROM account_invoice_reporte_solvmex rep,product_product,res_partner,account_invoice,res_users

WHERE [url removed, login to view] = rep.product_id

AND [url removed, login to view] = rep.partner_id

AND [url removed, login to view] = rep.numero_factura

AND [url removed, login to view] = account_invoice.user_id

AND account_invoice.date_invoice BETWEEN '2013-09-18' AND '2013-09-18'

order by default_code, monto_pesos

PostgreSQL

Nº del proyecto: #4980678

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