Asses with double obverses or double reverses first appeared under
Nero, but only began to be produced with some regularity under
Trajan, and lasted until the reign of
Commodus. See
Woytek,
Nero and the making of the
Roman medallion, Num. Chron. 171, 2011.
I suggested what I think is the first plausible explanation for these coins in my review of Woytek's
Trajan, Num. Chron. 172, 2012, p. 359: "I think such
asses may have been produced for use as New Year's gifts, the purpose of the doubled
obverse or
reverse type being to surprise the recipient, and to distinguish the gift from ordinary circulating
asses; perhaps more particularly to increase the coin's potency as a
good luck symbol, since it would allow the recipient to win every
coin flip!"
