Which of thiese paintings is a genuine van Gogh?

The original van Gogh (Dr. Gachet), painted in 1890. Sold at Christie's in 1990 for $75 Million

The copy, probably painted by Gachet himself.
Any one can see it. This is not an original van Gogh

© Preben Juul Madsen
www.artfakes.dk
2005