title: Python plot legend : markers appear twice
body: <p>A simple plot with a legend made with matplotlib produces the following: the markers at the left of the labels of my legend appear twice. Can anyone know why and how to avoid the problem? My command is:</p>
  
  <pre><code>pl.plot(x1,x2,'g^', label='regional')
  pl.plot(y1,y2,'bo', label='local')
  pl.legend( loc='upper left' )
  </code></pre>
  
  <p>Thank you</p>