Gallbladder duplication is a rare congenital biliary anomaly with different morphologies depending on events at embryogenesis. This case report describes a symptomatic duplicate gallbladder arising from the left intrahepatic duct 10 years after an open cholecystectomy: this is the rarest form of gallbladder duplication. The symptoms resolved following a second open cholecystectomy. This case illustrates the importance of preoperative imaging, intraoperative cholangiography, and a high index of suspicion of anomalous gallbladder anatomy in the diagnosis and management of this rare condition. We discuss the classification of anomalous gallbladder anatomy and review previous cases, to propose a modification of the common classification scheme.