This is BM 2010,5006.527 (acquired 1814 from the collection of Charles Townley)!
For a historical discussion and contextualization of the Velitrae finds (a
small deposit found at the church of S. Maria della Neve 1784 including both RRC 4/1 and 8/1), see Andreas Muran’s piece.
The BM records the inscription “Annotated in pen and ink at top: “Antichissima moneta di bronzo, trovata nel territorio d’Velletri, e conservata nella stessa citta nel Museo Borgiano. Pesa Libre [?] once 9 [?]” To my eye it clearly reads 4 pounds 9 ounces.
I believe this drawing to be the original from which Eckhel’s plate 9 was created.