This coin also looks suspect. See the text in the reference below for a fake one:
Fake Piastre de Commerce (Indochina) recto | Flickr - Photo Sharing!
Don...
Edit: Here's a real one: VSO - Indochine, 1 piastre, 1908 Paris - Monnaies - Monnaies coloniales :: iNumis - Numismate rue Vivienne Paris
Notice the difference in the size of the heads and where the dress line is on both 'coins' in relation to the exergue line.