Fix duplicated english names (Closes: #441)

src/celengine/body.cpp

@@ -160,10 +160,14 @@ void Body::setName(const string& name)
 /*! Add a new name for this body. Aliases are non localized.
  */
 void Body::addAlias(const string& alias)
+{
+    // Don't add an alias if it matches the primary name
+    if (alias != names[0])
     {
         names.push_back(alias);
         system->addAlias(this, alias);
     }
+}
 
 
 PlanetarySystem* Body::getSystem() const