This coin is a Constantine I campgate (VIRTVS AVGG) from Arles. It has been struck over another coin though. If you look closely at the second picture, which is rotated, you can make out much of the obverse legend of the original coin- DN VAL LICIN LICINIVS NOB C. You can also see the high crested helmet facing left, so it must be an IOVI CONSERVATORI. The mintmark is also legible SMNΓ, so the coin is RIC VII Nicomedia 49. 20x24mm 3.1gm
The IOVI coin was struck from A.D. 321- 324 and had half as much value as coins being struck in Constantinian mints and of course after the defeat of Licinius in A.D. 324, these coin would have been demonetized completely. Arles began striking VIRTVS campgates in A.D. 325; so this coin could have been overstruck pretty shortly after it was originally struck. I have seen these IOVI overstruck before with unofficial dies, but this one is in pretty good style. The third picture below has an official Arles campgate bust for comparison. The biggest difference is the base of the neck, which on the overstrike ends abruptly (maybe just due to the strike) versus the official coin which goes all the way to the edge of the coin and broadens out at the base.
An interesting coin which tells the story of the conflict between Licinius and Constantine, with Constantine coming out on top...literally!
