I was cataloguing this coin, which RIC IV says is from Milan. I thought it looked a lot more like Rome though. I did a little research and found this old article by R.A.G. Carson, "Mints in the mid-third century," in Essays Presented to Humphrey Sutherland, pp. 65-74. He wrote that there are die links that make this series a Rome issue, the last phase of that issue.
I bought this book years ago for other articles in it and don't remember if I even read the Carson article...of course, I may have forgotten it by now anyway.
Trajan Decius
A.D. 250- 251
AR Antoninianus
22mm 3.2gm
IMP CAE TRA DECIVS AVG; radiate, draped & cuirassed bust right.
PANNONIAE; the two Pannoniae, veiled, standing right and left facing one another, clasping right hands in front of standard between them.
RIC IV Milan [Rome] 41
