Yes, extremely. Last year there were almost 7.5 billion US pennies minted. Each is identical to every other. Ancient coin dies were cut by hand, so each die is unique. A typical die might be able to produce a few hundred coins before failing. Considering that most of these coins have been lost to history, there may be fewer than 100 coins stamped from the same die as yours left in the world. The coins were stamped by hand. Each stamp is unique. Of the hundred or so coins like yours still around, yours is the only one with that exact centering, relief and uniformity. So the fact is that you have the only coin in the world exactly like yours. Treasure it. Just don't assume that rarity necessarily translates into value. Kind in mind that every other ancient coin in the world is unique, too.
