Of course this fungibility is not an issue, until either a government or individuals begin to engage in a practice of changing value of coins based on demarcation, which is currently not an issue, but instead a speculation of an issue that could come up perhaps maybe blah blah blah.  And, also assuming that there is no way to remove history, then there is a way that coins could begin to look distinguishable from their history... but so far remains a BIG SO FUCKING WHAT?