Not my coin. Stumbled on it when looking at ebay. I know brockages exist on ancients but this looks weird to me. http://www.ebay.com/itm/162309750381?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Brockages are common in ancient coins, particularly coins of the Roman Republic. I don't see anything fishy about the linked coin, other than the too-high price.
The coin looks ok to me, but it is hard to tell from pics some times. The dealer did not do a good job of spell checking - "Error: Roman Republic, AR Dacrius, Rev. Full Mirror Brockage EC1842" The error is the name of the coin being sold, denarius.
The style is consistent with denarii of circa 130 BC. See this similar example. The style of Roma was very strange during this era.