XML:
<response>
	<item1>
		<item name="test1_1"/>
		<item name="test1_2"/>
		<item name="test1_3"/>
		<item name="test1_4"/>
		<item name="test1_5"/>
		<item name="test1_6"/>
	</item1>
	<item2>
		<item name="test2_1"/>
		<item name="test2_2"/>
		<item name="test2_3"/>
		<item name="test2_4"/>
		<item name="test2_5"/>
		<item name="test2_6"/>
	</item2>
</response>

XSLT:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
	<xsl:output method="xml" indent="yes" encoding="utf-8" omit-xml-declaration="yes"/>
	<xsl:template match="/">

	<response>
		<xsl:for-each select="/response/item1/item">
			<item>
				<xsl:attribute name="id"><xsl:value-of select="position()" /></xsl:attribute>
				<xsl:attribute name="name"><xsl:value-of select="./@name"/></xsl:attribute>
			</item>
		</xsl:for-each>
		<xsl:for-each select="/response/item2/item">
			<item>
				<xsl:attribute name="id"><xsl:value-of select="position()" /></xsl:attribute>
				<xsl:attribute name="name"><xsl:value-of select="./@name"/></xsl:attribute>
			</item>
		</xsl:for-each>
	</response>

	</xsl:template>
</xsl:stylesheet>


Result:
<response>
  <item id="1" name="test1_1">
  </item>
  <item id="2" name="test1_2">
  </item>
  <item id="3" name="test1_3">
  </item>
  <item id="4" name="test1_4">
  </item>
  <item id="5" name="test1_5">
  </item>
  <item id="6" name="test1_6">
  </item>
  <item id="1" name="test2_1">
  </item>
  <item id="2" name="test2_2">
  </item>
  <item id="3" name="test2_3">
  </item>
  <item id="4" name="test2_4">
  </item>
  <item id="5" name="test2_5">
  </item>
  <item id="6" name="test2_6">
  </item>
</response>