I bought this coin because of the scratch on the neck of Licinius. I do not, however, think that this was actually done because of damnatio memoriae. I think that this scratch was either accidental or just some graffitti, verus the official practice of damnatio memoriae, which usually obliterated an image or inscription, or inflicted serious gouges, not merely scratched it. This of course could have been done on purpose, perhaps by sopmeone that disliked Licinius, but that would have been coincidental to his damnatio memoriae.
I have never seen any 4th century coins that unequivocally looked like they were subjected to damnatio. In a fairly new book by Dario Calomino
Defacing the Past -- Damnation and Desecration in Imperial Rome, the author says that he has never seen a fourth century damnatio and explains that by the fourth century the practice of damnatio had become increasingly inconsistent.
For further consideration of the inconsistency of damnatio during the 4th century, look at the coins of some other rulers who were also DM'ed- Diocletian, Maximianus, Galerius, Severus II, Maximinus II, Maxentius, Crispus, Fausta, Constantine II, Constans, Magnentius and Magnus Maximus.
By the 4th century damnatio seemed to only mean that the person's name was never spoken and that they were never mentioned in historical records.
this Licinius coin was discussed a few years ago-
http://www.lateromanbronzecoinforum.com/index.php?topic=743.msg2182#msg2182
