Most people have just one pancreatic duct. However, some have an additional accessory pancreatic duct also called the Duct of Santorini, which connects straight to the duodenum at the minor duodenal papilla. Both these ducts connect to the second part (the vertical segment) of the duodenum.
However, the Duct of Santorini, which bypasses the Ampulla of Vater, is non-functional whereas the Duct of Wirsung is functional and carries the digestive enzymes released by the pancreas.
In some cases, the main pancreatic duct is smaller than the accessory pancreatic duct and the two may not be connected. In such people, the accessory duct carries most of the pancreatic juice.