The scientists compare a Black Sea Hoard coin, usually called fake, from Mesembria with a genuine example. The paper calls them hemiobols but they look like diobols.
... neither with phase proportions nor texture patterns can we distinguish between the two coins. The observed texture is consistent with ancient practice to produce coins by striking between two dies..... Therefore, no conclusions can be drawn about the authenticity of the coins....(via the Science & Coins page on the Robert Matthews Coin Authentication site.)