Part of the surviving obverse legend reads [CON]STANTINV[S], indicating Constantine I or Constantine II. Looks like they blundered the die, by the legend break and slight waviness in that area.
Checking the type, this is Constantine I. The bust is also Constantine I, you dont see it like that for Constantine II (the helmeted bust design changed by his reign).
Checking the type, this is Constantine I. The bust is also Constantine I, you dont see it like that for Constantine II (the helmeted bust design changed by his reign).























