I'm no numismatist but have spent many, many hours researching Roman coins. The obverse and reverse legends match 4 coins that I've found - RIC VII, Lugdunum 271, 276, 281 and 286 (with 271, 276 and 281 under Constantine II and 286 under Constantius II). The above coin doesn't seem to match any of them completely.
Obverse issues I see - Portrait most closely resembles RIC VII, Lugdunum 286 except the hair of the bust seems different. All the busts have finer hair and slightly different direction. The other issue is the lower right corner of the cuirass by the "C". This area most closely resembles RIC VII, Lugdunum 271 or 276.
Reverse issues I see - The plume from the helmet on the soldier on the left doesn't seem to match up to any of the RIC numbers. The other issue is the spoke that comes out of the lower part of the standard and the distance of it to the right soldier's shield seems to match RIC VII, Lugdunum 281.
COuld there be more varieties than I found? Yes. Could way the coin wore over time cause these issues? Not likely.