officially as part of a damnatio memoriae. If you're going to go to all the trouble of pulling a given emperor's coins out of circulation to (theoretically) deface them, wouldn't it be simpler/better just to keep them out of circulation ?! Even if the state preferred to deliberately keep "damned" emperor's coins in circulation, wouldn't it be quicker/cheaper/better to punch them with some kind of stamp rather than scratch/cut them ? Of course the actions of an individual (vs state representative executing a damnatio memoriae) are a different matter, but it's impossible to know anyone's motivation for defacing any given coin, regardless of whether the emperor on it had suffered damnatio or not.