A double or bilobar gallbladder is a rare congenital anomaly. If not recognized during preoperative evaluation or operation, it can cause severe complications. We describe two cases in which a second operation had to be performed because of the presence of a second or bilobar gallbladder that was not recognized in the preoperative evaluation and during (laparoscopic) cholecystectomy. The types of anomalies, the concomitant pathology, and treatment are discussed.