System Information
Windows 8

Blender Version
2.78

Short description of error
I have been trying to rig a model I made myself on blender using Rigify. However when I click on the button "generate" the controllers are generated twice, what makes complicated to distinguish wich one I should be selecting for continue with rigging or posing it. When I pose it the other bone stays in place...
-here I moved one to the side to see that-

I watched many tutorials and in none of them, this happened.

Exact steps for others to reproduce the error
Shift A > Armature > Human (meta-rig)
Fix bones' position
Click on armature tab menu "Generate"
*generates twice* <- Error