This topic was recently discussed on Moneta-L, but I think will also be of interest here.
Richard Schaefer called attention to an
Elephant denarius of
Julius Caesar, illustrated below, whose
obverse (
elephant side)
had been struck off center and oddly showed a portion of the
circle of dots of a SECOND
obverse die that
had apparently been sunk into the same piece of metal, alongside the main die.
Rick
Witschonke of the
ANS pointed out that
Bernhard Woytek had written an article in
German on precisely this subject in Schweizerische Numismatische Rundschau 85, 2006, pp. 69-96. Rick kindly sent me scans of the article, and I summarized it on Moneta-L as follows:
The phenomenon of a single coin showing on its
obverse the
impressions of two different dies that were evidently
engraved side by
side on the same anvil die has been observed on
Greek coins of a
wide geographical and chronological spread:
Segesta,
Sicily,
didrachm, late 5th cent. BC
Achaemenid sigloi struck in
Asia Minor, similar date
Seleucid hemidrachm, Alexander I Balas (150-145 BC)
Parthian drachm, Mithradates II (123-88 BC)
Many
Celtic coins, particularly silver coins struck in
Gaul in the
first cent. BC.
Actual
obverse dies of this nature for
Celtic coins, plates or cubes
of metal bearing two
obverse dies
engraved side by
side, have
recently turned up in two finds of
mint equipment in Bavaria, about
which a monograph is being prepared in
Munich!
A
dupondius of
Augustus and
Agrippa struck at
Nemausus shows the same
phenomenon of one coin showing impressions from two side-by-side
obverse dies, and
Woytek points to two
Elephant denarii of
Caesar,
the
Rauch specimen and one in the
Milan collection, that have the
same peculiarity.
Both of these
Elephant denarii are of "
poor style" and show the
elephant's two front legs and two
hind legs descending in parallel
from
his body to the ground. At least this group of coins will
certainly have been produced in
Gaul, where the use of multiple-image
obv. dies was evidently normal and widespread. This supports
Woytek's earlier conclusion, based on coin finds which show this
type only in the
west, that the
Elephant denarii must have been produced
in connection with Caesar's
Spanish expedition of the first half of
49 BC, doubtless partly using the silver that he confiscated from the
public treasury in
Rome after Pompey and
his partisans fled the city
early in that year.
The main group of
Elephant denarii, in better
style and with the
beast's fore and
hind legs descending to the ground at an angle from
each other like two Greek lambdas, does not show double
obv. dies
even when the obverses are struck badly off center. They must have
been struck at a different
mint, using single- rather than double-
image
obv. dies, which
Woytek thinks may also have been located in
southern
Gaul.
What was the purpose of using double-image
obv. dies?
Woytek rejects
Crawford's suggestion that they may have been coupled with double-
image
rev. dies, so that two coins could be struck
side by
side at
the same time. The fact that the two images on the
obv. die were
generally right next to each other speaks against another hypothesis,
that coins may have been struck alternately from the two images to
prevent the
obv. die from overheating.
Woytek finally admits
ignorance: obviously the two images must have made the production
process more efficient in some way, but no one yet has been able to
explain exactly how.
Curtis Clay
The second picture below shows an
elephant denarius of
fine style and with forelegs and
hind legs at different angles, the sort of coin that was apparently NOT struck from double-image
obverse dies.