XSLT: Remove duplicate nodes based on name attribute

Question

I have the following:

<xs:schema>
<xs:complexType name="NameType">
 <xs:sequence>
  <xs:element name="NamePrefix" type="core:NamePrefixType" minOccurs="0"/>
  <xs:element name="FirstName" type="core:FirstNameType" minOccurs="0"/>
  <xs:element name="MiddleName" type="core:MiddleNameType" minOccurs="0" maxOccurs="10"/>
  <xs:element name="LastName" type="core:LastNameType" minOccurs="0"/>
  <xs:element name="NameSuffix" type="core:NameSuffixType" minOccurs="0"/>
  <xs:element name="NameTitle" type="core:NameTitleType" minOccurs="0"/>
  <xs:element name="CompositeName" type="core:CompositeNameType" minOccurs="0"/>
  <xs:element name="NoteMessage" type="core:NoteMessageType" minOccurs="0" maxOccurs="unbounded"/>
 </xs:sequence>
</xs:complexType>
<xs:simpleType name="NamePrefixType"/>
<xs:simpleType name="FirstNameType"/>
<xs:simpleType name="MiddleNameType"/>
<xs:simpleType name="LastNameType"/>
<xs:simpleType name="NameSuffixType"/>
<xs:simpleType name="NameTitleType"/>
<xs:simpleType name="CompositeNameType"/>
<xs:simpleType name="NoteMessageType"/>
<xs:complexType name="NameType">
 <xs:sequence>
  <xs:element name="NamePrefix" type="core:NamePrefixType" minOccurs="0"/>
  <xs:element name="FirstName" type="core:FirstNameType" minOccurs="0"/>
  <xs:element name="MiddleName" type="core:MiddleNameType" minOccurs="0" maxOccurs="10"/>
  <xs:element name="LastName" type="core:LastNameType" minOccurs="0"/>
  <xs:element name="NameSuffix" type="core:NameSuffixType" minOccurs="0"/>
  <xs:element name="NameTitle" type="core:NameTitleType" minOccurs="0"/>
  <xs:element name="CompositeName" type="core:CompositeNameType" minOccurs="0"/>
  <xs:element name="NoteMessage" type="core:NoteMessageType" minOccurs="0" maxOccurs="unbounded"/>
 </xs:sequence>
</xs:complexType>
<xs:simpleType name="NamePrefixType"/>
<xs:simpleType name="FirstNameType"/>
<xs:simpleType name="MiddleNameType"/>
<xs:simpleType name="LastNameType"/>
<xs:simpleType name="NameSuffixType"/>
<xs:simpleType name="NameTitleType"/>
<xs:simpleType name="CompositeNameType"/>
<xs:simpleType name="NoteMessageType"/>

How can I integrate duplicate node handling based on the following xsl:

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="core AcRec">

 <xsl:template match="/xs:schema">
   <xsl:copy>
     <xsl:apply-templates />
     <xsl:copy-of select="//xs:simpleType" />
   </xsl:copy>
 </xsl:template>

 <xsl:template match="*[name()!='xs:simpleType' and name()!='xs:schema']">
   <xsl:copy>
     <xsl:apply-templates select="*|@*"/>
   </xsl:copy>
 </xsl:template>

  <xsl:template match="@*">
    <xsl:copy-of select="." />
  </xsl:template>    
</xsl:stylesheet>

Expected output:

<xs:schema>
  <xs:complexType name="NameType">
    <xs:sequence>
      <xs:element name="NamePrefix" type="core:NamePrefixType" minOccurs="0"/>
      <xs:element name="FirstName" type="core:FirstNameType" minOccurs="0"/>
      <xs:element name="MiddleName" type="core:MiddleNameType" minOccurs="0" maxOccurs="10"/>
      <xs:element name="LastName" type="core:LastNameType" minOccurs="0"/>
      <xs:element name="NameSuffix" type="core:NameSuffixType" minOccurs="0"/>
      <xs:element name="NameTitle" type="core:NameTitleType" minOccurs="0"/>
      <xs:element name="CompositeName" type="core:CompositeNameType" minOccurs="0"/>
      <xs:element name="NoteMessage" type="core:NoteMessageType" minOccurs="0" maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>
  <xs:simpleType name="NamePrefixType"/>
  <xs:simpleType name="FirstNameType"/>
  <xs:simpleType name="MiddleNameType"/>
  <xs:simpleType name="LastNameType"/>
  <xs:simpleType name="NameSuffixType"/>
  <xs:simpleType name="NameTitleType"/>
  <xs:simpleType name="CompositeNameType"/>
  <xs:simpleType name="NoteMessageType"/>
</xs:schema>

Answer 1

This copies the first distinct simpleType of any name but is a bit more explicit with the 'NameType' complexType:

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="core AcRec"
    xmlns:core="foo" xmlns:AcRec="bar">

    <xsl:key name="simpleTypes" match="xs:simpleType" use="@name"/>

    <xsl:template match="/xs:schema">
     <xsl:copy>
      <xsl:copy-of select="xs:complexType[@name='NameType'][1]"/>
      <xsl:apply-templates />
      <xsl:copy-of select="//xs:simpleType[generate-id(.) = generate-id(key('simpleTypes', @name)[1])]" />
     </xsl:copy>
    </xsl:template>

    <xsl:template match="*[name()!='xs:simpleType' and name()!='xs:schema' and @name!='NameType']">
     <xsl:copy>
      <xsl:apply-templates select="*|@*"/>
     </xsl:copy>
    </xsl:template>

    <xsl:template match="@*">
     <xsl:copy-of select="." />
    </xsl:template>

    <xsl:template match="*"/>
</xsl:stylesheet>

Note that the default template is overridden so that you don't get the undesired children of 'NameType'.