multigraph
/ˈmʌltɪɡrɑːf/ /ˈmʌltɪɡraf/noun
1A machine for making multiple copies of a document; especially a small printing machine which uses specially cast type fitted in grooves on a rotating cylinder. Now historical.
2 Mathematics. A graph in which two vertices may be connected by more than one edge.
Origin
Late 19th century; earliest use found in The Trade Marks Journal.