XSLT1.0 Remove repeat nodes - xslt-1.0

Question

I am trying to apply Muenchian grouping to eliminate duplicate nodes, but I seem not to be able to make it work.
Input:
<GetUsersByRoleRspMsg>
<UserList>
<User>
<UserId>PPAUSER1</UserId>
<Email>xyz#gmail.com</Email>
</User>
<User>
<UserId>PPAUSER1</UserId>
<Email>xyz#gmail.com</Email>
</User>
</UserList>
</GetUsersByRoleRspMsg>
Required:
<GetUsersByRoleRspMsg>
<UserList>
<User>
<UserId>PPAUSER1</UserId>
<Email>xyz#gmail.com</Email>
</User>
</UserList>
</GetUsersByRoleRspMsg>
The critical part of my code is
<xsl:key name="userIdEmailPair"
match="User"
use="concat(UserId,' ',Email)"/>
<xsl:copy>
<xsl:for-each select="User[
count(. | key('userIdEmailPair',
concat(UserId,' ',Email))[1])
= 1]">
<xsl:copy-of select="."/>
</xsl:for-each>
</xsl:copy>

Answer 1

I don't see any problem with your grouping code. If you try:
<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:strip-space elements="*"/>
<xsl:key name="userIdEmailPair" match="User" use="concat(UserId,' ',Email)"/>
<!-- identity transform -->
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="UserList">
<xsl:copy>
<xsl:for-each select="User[count(. | key('userIdEmailPair',concat(UserId,' ',Email))[1]) = 1]">
<xsl:copy-of select="."/>
</xsl:for-each>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
you will get the result you're looking for.
Of course, you could shorten the last template to:
<xsl:template match="UserList">
<xsl:copy>
<xsl:copy-of select="User[count(. | key('userIdEmailPair',concat(UserId,' ',Email))[1]) = 1]"/>
</xsl:copy>
</xsl:template>