They do not share
flan shapes and thus do not exhibit that facet of casts that we use so easily to detect modern casts. If they have been struck from transfer dies then I have never seen the originals that they are based on. The four
Probus coins are all unlisted for various reasons, the
PROVIDENTIA AVG being an unlisted coin from
Siscia and the others are simply unlisted variations from
Rome which in itself isn't that unusual. I think they have used a mix of
obverse dies and
reverse dies to create unlisted coins in order to increase their appeal. The
style is too
good (I can recognise the mints from the
bust styles) to be modern hand crafted dies and so must be based on original coins somewhere down the line.
Just some initial rambling thoughts.
Martin