Somehow I missed this before (late-August was quite busy for me). There's a new hoard of fakes on the market of common late Roman bronze. Examples are found for Probus, Carus, Constantine, Constantine II, and Constans so far. They were discovered as fakes by astute dealers who noticed the ubiquitous die matches, the uniform repatination, and the identical flan-shapes.
As of yet, I see no easy way to distinguish these from genuine coins, given a single example. The dies were likely transfer directly from high-grade, official coins, so the style is perfect. However, there are a number of mules (probably to sell these as "not in RIC" varieties), including mixed mints (ie, Siscia style portrait with Rome mintmarks) and mixed legends (ie, IMP...CAES on the obv, VIRTVTI AVG on the reverse).
Thankfully, all of the specimens have come on the market since late summer, so anything before that should be fine. In addition, this hoard is well documented:
http://www.wildwinds.com/coins/ric/fakes2009.htm
And the two threads where these were discovered:
http://ancients.info/forums/showthread.php?t=2671 http://www.forumancientcoins.com/boa...?topic=55135.0
Of course, there's no need to panic. Just remain cautious and use your KNOWLEDGE to catch these counterfeits!