Isn't this obvious ?
There is A:
The collectors aspect.If official, this coin might have been published in the next
RIC issue, coming from the nd
collection; something to be proud of.
B:
The historical aspect.A official coin was minted during a specific reign, circulated during this reigen, and often was issued for a historical event; a
victory, anther year as
consul, a marriage etc...
Such a coin might actually be the only source for such an historical event.
The imitation might be ancient but not necessarily from this reign, and an unusual obverse/reverse combination means what? Nothing!
enough reasons ?
Imitations are interessting if they are issued by e.g. a certain
celtic tribe and created by artists with their own
style. These coins have their own
history. Imitations which were produced by criminals in an unkown cellar are just that and nothing more.