Each side has both the obverse and the reverse. I think it's a double flip error or something like that. It's really cool! Erin
Not exactly damage, but an interesting planchet flaw on my Ptolemy III. From the seller's original description: "This is an interesting coin as in the Ptolemaic era all bronze planchets were first cast in various sizes and then a punch was made on the obverse and reverse to steady the die when striking was done. In this case there was an air bubble in the planchet and when the obverse was punched the air bubble was hit so it was punched again." There is a cavity in this coin large enough to hide a Jeep Cherokee!
I'm not sure I would include corrosion as "damage" - this was not something done deliberately as the banker-marks, test cuts, Memoriae Damnatio ancient holing and things of that nature. For example, and I don't want to seem to be calling anyone out here, but that Trajan Egyptian dichalcon came from the mint like that and was not in the least unusual in terms of just being issued with sloppy workmanship - probably the Byzantine coin following it was also that same shape the moment it left the dies. I'd propose that for examining things of this nature, we'd need to sub-divide the subject into "classes", test cuts and banker-marks could have a class. I'm not sure I'd call counter marking ancient damage, but you might distinguish between those carelessly countermarked just anywhere as opposed to carefully sited as it is on that nice confronted busts piece. Graffiti, and odd, relatively insignificant markings like the homemade "reeding" on the edge of one specimen fall into a completely different class than those deliberately marked for Damnatio, or the ones which have obviously been profoundly altered like the Alexander Æ with the Mondrian-like engraved lines on the planed obverse, or like this proto-contorniate made from a Nero sestertius: http://www.stoa.org/gallery/album89/mark_nero_sestertius_2?full=1 Someone - or several someones - lavished "after-market alterations" onto this Nero piece, but whether this occurred in "antiquity" or was merely done sometime out of living memory is not strictly determinable. This Marcus Aurelius, on the other hand, was almost certainly a watch-fob in the late 19th/early 20th century as, when I found it in an odd little "occult shop" in Provincetown, it had 3 or 4 links of brass chain attached through the hole: http://www.stoa.org/gallery/album94/ML12_M_Aurel_Vota_Pub_sest In fact, I suppose you could make an entire organized sub-genré of "deliberately altered" coins, not unlike those of exonumia or mint-errors.