This paper explores the dual coinage struck by Byzantium and Chalcedon featuring the head of Demeter on the obverse and a local deity on the reverse. Previously these two coinages were seen as a type of short-lived emergency measure intended to raise funds for Byzantium during the third quarter of the 3rd century BC. However, using a revised and updated die study of Byzantium's “Demeters” based on the work of Schoenert-Geiss and a never before completed study of Chalcedon's “Demeters”, I intend to show that these parallel series continued in circulation for an extended period of time. Furthermore, although struck on a different weight standard, sometimes called "Phoenician", the “Demeters” were minted alongside the Attic-weight Lysimachi coinages of both cities. This provides further proof that Byzantium and Chalcedon carefully orchestrated their coinages and employed different types of coins to fulfil diverse needs.