Separate duplicates from unique - xslt

Question

I tried with many XSLT methods like Key, for-each-group and match method options, but it is not working for me.
Input XML:
<?xml version='1.0' encoding='UTF-8'?>
<CustomerRecord>
<Customer>
<chargeto>ABC</chargeto>
<chargename>GARY</chargename>
</Customer>
<Customer>
<chargeto>XYZ</chargeto>
<chargename>DAVIS</chargename>
</Customer>
<Customer>
<chargeto>CDE</chargeto>
<chargename>GARY DAVIS</chargename>
</Customer>
<Customer>
<chargeto>ABC</chargeto>
<chargename>DAV</chargename>
</Customer>
</CustomerRecord>
Expected output XML:
<?xml version='1.0' encoding='UTF-8'?>
<Root>
<Customer_PO>
<Customer>
<chargeto>ABC</chargeto>
<chargename>GARY</chargename>
</Customer>
<Customer>
<chargeto>ABC</chargeto>
<chargename>DAV</chargename>
</Customer>
</Customer_PO>
<Customer_Falty>
<Customer>
<chargeto>XYZ</chargeto>
<chargename>DAVIS</chargename>
</Customer>
<Customer>
<chargeto>CDE</chargeto>
<chargename>GARY DAVIS</chargename>
</Customer>
</Customer_Falty>
</Root>
Below is the XSLT which I wrote Initially to at least get the some details in the Output, but data is getting missed when the target is generated:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:var="http://schemas.microsoft.com/BizTalk/2003/var" exclude-result-prefixes="msxsl var" version="1.0" xmlns:ns0="http://Namespace">
<xsl:output omit-xml-declaration="yes" method="xml" version="1.0" />
<xsl:key use="chargeto" match="/CustomerRecord/Customer" name ="groups"/>
<xsl:template match="/">
<xsl:apply-templates select="/CustomerRecord" />
</xsl:template>
<xsl:template match="/CustomerRecord">
<Root>
<xsl:for-each select="/CustomerRecord/Customer[generate-id(.)=generate-id(key('groups',chargeto))]">
<Customer_PO>
<xsl:for-each select="key('groups',chargeto)">
<Customer>
<chargeto>
<xsl:value-of select="CustomerRecord/chargeto/text()" />
</chargeto>
<chargename>
<xsl:value-of select="CustomerRecord/chargename/text()" />
</chargename>
</Customer>
</xsl:for-each>
</Customer_PO>
</xsl:for-each>
</Root>
</xsl:template>
</xsl:stylesheet>
Please find the explanation about the Expected Output
<Customer_PO>. Under this tag we will have all the <Customer> segments where all the <chargeto> fields are having duplicate value
<Customer_Falty> Under this tag we will have all the <Customer> segment where all the <chargeto> field values are unique

Answer 1

If I understand correctly your explanation, you want to do something like:
XSL 1.0
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:key name="cust-by-charge" match="Customer" use="chargeto" />
<xsl:template match="/CustomerRecord">
<Root>
<Customer_PO>
<xsl:copy-of select="Customer[count(key('cust-by-charge', chargeto)) > 1]"/>
</Customer_PO>
<Customer_Falty>
<xsl:copy-of select="Customer[count(key('cust-by-charge', chargeto)) = 1]"/>
</Customer_Falty>
</Root>
</xsl:template>
</xsl:stylesheet>
Possibly there's a more elegant approach that would count the size of each group only once.