private boolean existingGrammars(Vector grammars) {
        int length = grammars.size();
        final XSDDescription desc = new XSDDescription();

        for (int i=0; i < length; i++) {
            final SchemaGrammar sg1 = (SchemaGrammar)grammars.elementAt(i);
            desc.setNamespace(sg1.getTargetNamespace());

            final SchemaGrammar sg2 = findGrammar(desc, false);
            if (sg2 != null) {
                return true;
            }
        }

        return false;
    }