```xslt
<?xml version="1.0" encoding="UTF-8"?>
<!--
This file is part of the DITA Open Toolkit project.

Copyright 2014 Jarno Elovirta

See the accompanying LICENSE file for applicable license.
-->
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="2.0">

  <xsl:import href="plugin:org.dita.xhtml:xsl/dita2xhtml.xsl"/>
  <xsl:import href="plugin:org.dita.xhtml:xsl/map2html-coverImpl.xsl"/>

  <!--xsl:output method="xhtml"
              encoding="UTF-8"
              doctype-system="http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
              doctype-public="-//W3C//DTD XHTML 1.0 Transitional//EN"/-->

  <xsl:include href="plugin:org.dita.xhtml:xsl/dita2xhtml-util.xsl"/>

</xsl:stylesheet>
```

Remove duplicate dita2xhtml-util.xsl include from cover stylesheet
user
```xslt
<?xml version="1.0" encoding="UTF-8"?>
<!--
This file is part of the DITA Open Toolkit project.

Copyright 2014 Jarno Elovirta

See the accompanying LICENSE file for applicable license.
-->
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                version="2.0">

  <xsl:import href="plugin:org.dita.xhtml:xsl/dita2xhtml.xsl"/>
  <xsl:import href="plugin:org.dita.xhtml:xsl/map2html-coverImpl.xsl"/>

  <!--xsl:output method="xhtml"
              encoding="UTF-8"
              doctype-system="http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
              doctype-public="-//W3C//DTD XHTML 1.0 Transitional//EN"/-->

  <!--xsl:include href="plugin:org.dita.xhtml:xsl/dita2xhtml-util.xsl"/-->

</xsl:stylesheet>
```
assistant