Duplication of common bile duct is a rare entity and its association with distal cholangiocarcinoma is extremely rare. It represents failure of regression of the embryological double biliary system. Here, we describe the diagnostic and therapeutic challenges of a type I variant of the extrahepatic bile duct duplication coexistent with distal cholangiocarcinoma that was diagnosed intraoperatively while treating with Whipple procedure for distal cholangiocarcinoma.