Matplotlib Legend has two stars

I usually make it like this when I take only one dot in matplotlib

from matplotlib.pyplot import *

x = 10
y = 100
plot(x, y, "k*", label="Global Optimum")
legend()
show()

But when I did this, the star was marked twice like * * Global Optimum on the legend.

I want to make * Global Optimum appear only once, but how can I reduce the number of stars?