Ureteral duplication is a common embryologic abnormality of the kidney with an incidence rate of 0.8% in adults. However, complete duplex ureters opening independently into the urinary bladder are rarely present. We report a 35-year-old female who presented with left flank pain in the last three years. Abdominal CT scan showed left complete duplicated system with lower moiety hydroureteronephrosis and obstructed midureteral stone. The patient underwent left retroperitoneal exploration with complete excision of the hydronephrotic sac. The postoperative course was uneventful without complications. In conclusion, a complete duplex kidney with lower moiety hydronephrosis caused by mid ureteric stone is rare. The renal duplication system should be diagnosed and followed with image guidance periodically as the late diagnosis may have poor outcomes with loss of the kidney or part of it.