Of course the coin could be real and NGC can be wrong. They state themselves there is no way to be 100% certain with ancients sometimes. And have a disclaimer:
"NGC Ancients is committed to grading only genuine coins, but it does not guarantee authenticity, genuineness or attribution, nor is any guarantee of these aspects implied. NGC Ancients will only holder coins it considers genuine at the time of submission, but it cannot guarantee the authenticity, genuineness, type, attribution or date of any coin it holders. Unlike modern coins, which often benefit from well-documented, scientific parameters for the verification of authenticity, there rarely is conclusive data for ancient coins, and generally there is no surviving documentation to verify production characteristics."