This mintmark is unlisted in RIC for bust type H11, it should be before RIC 61. I have had several examples though and there were four examples of this type in the Bikic-Do hoard, # 198- 201-- one from officina A, one from B, and two from epsilon.
It has been struck on a large flan and the reverse also has a double strike.
Constantine I
A.D. 319
21mm 3.3gm
IMP CONSTANT-INVS AVG; high crested helmet and cuirassed bust left with spear across right shoulder.
VICTORIAE LAETAE PRINC PERP; two Victories stg., facing one another, together holding shield inscribed VOT PR on altar.
In ex. ESIS dot
RIC VII Siscia --