Wikipedia
Accessory pancreatic duct
Most people have just one pancreatic duct. However, some have an additional accessory pancreatic duct also called the Duct of Santorini, which is dorsal and usually (in 70%) drains into to the duodenum via the minor duodenal papilla. In the other 30% it drains into the main pancreatic duct, which drains into the duodenum via the major duodenal papilla. The main pancreatic duct and the accessory duct both eventually - either directly or indirectly - connect to the second part ('D2', the vertical segment) of the duodenum.
The Duct of Santorini is commonly non-functional, whereas the Duct of Wirsung is always functional when present. The two may not be connected.
It is named for Giovanni Domenico Santorini.