Below, I added links to the authentic (I assume

) piastre from the Numista catalogue. Especially when you open both images in separate browser tabs and compare, you see that the left one is lacking a lot of depth and detail. Main points of attention: the face of the lady, the fasces, the wreath on the reverse and the lettering (which is so much lighter, it seems). This may be due to the quality of the image, but I don't think so.
The left one also has remarkable and irregular
burrs around the edges, as if it was manufactured with little care for detail, and it hasn't passed through a lot of hands ever since.
It would seriously surprise me if it turned out to be authentic, but I don't feel confident enough to bluntly say that it's a fake. But I do think so.
By the way, if you're interested, there are a lot of forum topics on distinguishing fakes (with the Indochinese piastre featuring as a regular guest), e.g.
https://en.numista.com/forum/topic32491.html
https://en.numista.com/forum/topic30327.html
https://en.numista.com/forum/topic24607.html
https://en.numista.com/forum/topic7217.html

