here's an unofficial issue that just sold in the latest ROMA auction. I'm not sure if they realized it was unofficial.
"Constantine I BI Mule Nummus. Treveri, AD 310-313(?). IMP CONSTANTINVS AVG, cuirassed bust to left, wearing high-crested helmet, holding spear across right shoulder and shield on left arm / OVI CONSERV[ATORI AVG], Jupiter astride eagle to right, head reverted, holding thunderbolt and sceptre; ST[R]in exergue. RIC -, cf. 825 (Licinius I). 2.41g, 17mm, 2h.
Very Fine. Extremely Rare, possibly unique.
From a private UK collection.
This coin appears to utilise an obverse of Constantine I with a reverse of Licinius I."
