The first to tentatively attribute a Ptolemaic type (Svoronos 612) to Hieron II of Syracuse was Wolfram Weiser from Cologne. (W. Weiser, in : Katalog ptolemäischer Bronzemünzen der Sammlung des Instituts für Altertumskunde der Universität zu Köln, Papyrologica Coloniensia XXIII.)
Cathy Lorber and Daniel Wolf agree and have also attributed some additional Ptolemic types, including this type, as Hieron II imitatives.
Wolf and Lorber note, 'the coins are distinguished from other types of Ptolemaic bronze diobols by artistic style, anomalous (variable) die axes, and (almost always) circular reverse borders.
They are found almost exclusively in Sicily. They also share size, weight, die axis variability, and control marks with some bronze portrait coins of Hieron II...
Hieron may have struck the imitative coins to trick his mercenaries into believing that they were on the payroll of Ptolemy II. If the veteran soldiers distrusted their commander, they would probably have demanded their pay in precious metal currency. The ruse of pseudo-Ptolemaic bronze coins perhaps enabled Hieron to pay his mercenaries in a fiduciary coinage they would not otherwise have accepted...'
for details of the attribution see: http://www.megagem.com/ancient/paper.html