Hello Pierre and welcome.
I saw that coin when it was up for auction and my first impression was that it seemed odd. It is hard to be sure from just a picture and perhaps you will have a better idea when you get it, but it does not seem correct for an ancient coin.
However, my impression may have been strongly influenced by there not being a mintmark, which may only be the result of a weak strike. The lighting is not doing the picture any favors either, but the surfaces look too smooth, especially the reverse. The edges of the flan also look very smooth, when I would expect an ancient struck flan to look more irregular.
