Nova Roma Commemorative) both @Heliodromus and I discussed the possibility that the VRBS ROMA/two soldier and the CONSTANTINOPOLIS/two soldier hybrid coins may have been minted during the 3-4 month interregnum between the death of Constantine I and ascension of his son to Augusti. I went through RIC VII and RIC VIII and tracked down all the listings of these hybrid coins and noted where they were minted and their mint marks. In most cases the hybrids overlapped the two volumes. That is, they had the same mint marks and were minted in the same officinas in both volumes. Basically this means that the hybrids could have been minted anytime between 336-340 A.D. The one exception is Heraclea, where a few coins with a dot at the end are listed in RIC VIII but not in RIC VII, suggesting that these could not have been minted during Constantine's lifetime (if these few, rare examples actually exist). So the suggestion that these hybrids were minted during the interrugnum cannot be proven by reviewing the mint marks, but it cannot be dismissed, either. The possibility remains. For now.