Piwo dubeltowe

double malt beer; beer with twice the amount of malt compared to ordinary beer.

Source: “For a barrel of dubeltowe beer, for three barrels of cienkusz.”  AGAD, Akta osób i rodzin, ref. no. 237, Regestra percepty…

See also: J. Roszko, Produkcja alkoholi…, pp. 463–492.