Material like this triggers so many questions. Hoards show that these copies circulated with the official coinage. Your metallurgic analyses show that they must have been valued similarly. We can therefore assume a similar survival rate for official and unofficial coins. Apart from in hoards with coins fresh from the mint, it is not easy to find four late Roman coins from the same dies. In my material from the Rome mint, which for certain periods includes virtually every specimen known in museums and private hands, each die is known from on average a few coins at most, and it is rare with four double die matched examples. The highest number of double die-matched coins is below ten.
These circumstances clearly indicate that these unofficial copies were produced in huge numbers, with the output per die equaling or exceeding the numbers produced in the imperial mints.
This in turn shows that the unofficial dies were of a quality, hardness and durability comparable to the official dies. The "barbarians" producing the "barbarous" copies, must have been as skilled metalworkers as the Romans.
For one, the "barbarous" copies were often (always?) silvered, like the official coins. Even now, we have no idea how this was done (although a profusion of ideas have been forwarded).
Another line of thought: the official mints collected coins that no longer could circulate as official coinage (for example the eastern IOVI coins of Licinius were not accepted in the west and were regularly overstruck at the official mints to make regular coinage. Victor's metallurgical analyses seem to indicate that the barbarians" also collected such coins and used the metal to strike their copies. This raises many questions.
Why on earth would they do that? Did they sit on enormous amounts of old or unaccepted bronze coins? Outside the limes, did they even use coins for monetary purposes? From the uniface gold medallions struck by Constantine and others for the "barbarian" leaders we know that they were not using gold as coinage. And bronze?
If they produced the millions of "barbarous" copies not for themselves but for use as coins in areas where also official coinage circulated, there must have been a profit involved. If they didn't sit on tons of coins that were no longer permitted to circulate, did they specifically import such coins from other areas of the empire? Seems very far fetched. So where did they get the coins to melt and re-strike?
Another line of thought: Did the "barbarous" copies fill a need? Was there a shortage of coins when they were produced? If so, why wasn't that shortage taken care of by the imperial mints? The output at the imperial mints varied enormously, as a response to need. Whenever there was a need to pay troops (poor guys, getting bronze coins rather than the stipulated silver and gold, but that must have been the case), the official output increased manyfold (for example during each war between Constantine and his co-emperors). This shows that any shortage of coinage was easily taken care of by the imperial mints.
So shortage of coinage cannot explain the production of "barbarous" coins.
Sorry that I produce many more questions than answers. One question leads to another, and another. I can't remember having seen a detailed discussion of these questions. This should be the topic for a PhD for a student somewhere.
