duplicatum jus

from Bouvier's Law Dictionary, Revised 6th Ed (1856)
DUPLICATUM JUS, a twofold or double right. Those words, according to 
Bracton, lib. 4, c. 3, signify the same as dreit dreit, or droit droit, and 
are applied to a writ of right, patent, and such other writs of right as are 
of the same nature, and do, as it were, flow from it, as the writ of right. 
Booth on Real Actions, 87. 
    

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