FEL TEMP coins from Constantinople with unusual fieldmarks

[Victor]

I noticed this coin (RIC VIII Constantinople 92) the other day that struck me as odd. It is a common FEL TEMP from Constantinople with a gamma in the left field. This would seem to be a workshop, except that is included in the exergue- the first coin below reads CONS gamma star- so why another gamma in the left field? Earlier FTR issues starting with Constantinople 79 also have unusual field marks- Constantius II always has a gamma in the left field for his issues, while Constans always has an S on his coins. RIC notes this in the preface to Constantinople, but offers no conjecture on why.