Are "role" and "type" duplicated in the 5.0 XML schema?

docbook.xsd contains:

<xs:attributeGroup name="db.common.linking.attributes">...
    <xs:attribute ref="xlink:type"/>
    <xs:attribute ref="xlink:role"/>

and several docbook element definitions contain

<xs:element name="...">
   <xs:complexType mixed="true">
      ...
      <xs:attribute name="role"/>              <!-- or name="type" -->
      <xs:attributeGroup ref="docbook:db.common.linking.attributes"/>
  </xs:complexType>
</xs:element>

which, although unusual, is technically correct since one attribute is
in namespace  "http://docbook.org/ns/docbook" and the other one in
"http://www.w3.org/1999/xlink".

But it is apparent from the docbook spec that this is unintentional
and therefore I think that the redundant <xs:attribute> elements
should be omitted. Is this correct?

-W