code: public static boolean deleteDuplicatedQualfiier(Feature feature, String qualifierName)
  	{
  		ArrayList<Qualifier> qualifiers = (ArrayList<Qualifier>) feature.getQualifiers(qualifierName);
  		Set<String> qualifierValueSet = new HashSet<String>();
  
  		for (Qualifier qual : qualifiers)
  		{
  			if (qual.getValue() != null)
  			{
  				if (!qualifierValueSet.add(qual.getValue()))
  				{
  					feature.removeQualifier(qual);
  					return true;
  				}
  			}
  
  		}
  		return false;
  
  	}
docs: Delete duplicated qualfiier.
  
  @param feature
  the feature
  @param qualifierName
  the qualifier name