XSLT 1.0 - Remove Duplicate Nodes From Variable - xslt

Question

I've seen many posts on this, but none of them have helped me figure out my problem.
Test1.xml
<table>
<row>
<col1>A</col1>
</row>
<row>
<col1>B</col1>
</row>
<row>
<col1>C</col1>
</row>
</table>
Test2.xml
<table>
<row>
<col1>A</col1>
<col2>ABC</col2>
</row>
<row>
<col1>B</col1>
<col2>ABC</col2>
</row>
<row>
<col1>A</col1>
<col2>ABC</col2>
</row>
<row>
<col1>C</col1>
<col2>ABC</col2>
</row>
<row>
<col1>A</col1>
<col2>DEF</col2>
</row>
</table>
Test.xsl (XSLT 1.0)
<xsl:variable name="input" select="document('test1.xml')/>
<xsl:template match="/">
<xsl:apply-templates select="$input" mode="special"/>
</xsl:template>
<xsl:template match="node()|#" mode="special">
<xsl:copy>
<xsl:apply-templates select="node()|#" mode="special"/>
</xsl:copy>
</xsl:template>
<xsl:template match="Row" mode="special">
<xsl:variable name="cols" select="document('test2.xml')/Table/Row[current()/Col1 = Col1]/Col2"/>
<xsl:variable name="unique_cols" select="$cols[not(. = preceding-sibling::*)]"/>
<!-- Debug -->
<xsl:for-each select="$unique_cols">
<xsl:copy-of select="."/>
</xsl:for-each>
----
</xsl:template>
Expected Output:
<col2>ABC</col2>
<col2>DEF</col2>
----
<col2>ABC</col2>
----
<col2>ABC</col2>
Current Output:
<col2>ABC</col2>
<col2>ABC</col2>
<col2>DEF</col2>
----
<col2>ABC</col2>
----
<col2>ABC</col2>
The col2 values in $unique_cols should be distinct per col1 values. If unique col2 values could be selected in $cols, even better.

Answer 1

Just replace:
<xsl:variable name="unique_cols" select="$cols[not(. = preceding-sibling::*)]"/>
with:
<xsl:variable name="unique_cols" select=
"$cols[not(../col1 = ../preceding-sibling::*/col1)]"/>
The full transformation (initially corrrected to fix a multitude of lexical errors) now becomes (also using my own file-Uris):
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:variable name="input" select=
"document('file:///c:/temp/delete/test1.xml')"/>
<xsl:template match="/">
<xsl:apply-templates select="$input" mode="special"/>
</xsl:template>
<xsl:template match="node()|#*" mode="special">
<xsl:copy>
<xsl:apply-templates select="node()|#*" mode="special"/>
</xsl:copy>
</xsl:template>
<xsl:template match="row" mode="special">
<xsl:variable name="cols" select=
"document('file:///c:/temp/delete/test2.xml')
/table
/row[current()/col1 = col1]
/col2"/>
<xsl:variable name="unique_cols" select=
"$cols[not(../col1 = ../preceding-sibling::*/col1)]"/>
<!-- Debug -->
<xsl:for-each select="$unique_cols">
<xsl:copy-of select="."/>
</xsl:for-each>
----
</xsl:template>
</xsl:stylesheet>
and the files are:
c:/temp/delete/test1.xml:
<table>
<row>
<col1>A</col1>
</row>
<row>
<col1>B</col1>
</row>
<row>
<col1>C</col1>
</row>
</table>
and: c:/temp/delete/test2.xml:
<table>
<row>
<col1>A</col1>
<col2>ABC</col2>
</row>
<row>
<col1>B</col1>
<col2>ABC</col2>
</row>
<row>
<col1>A</col1>
<col2>ABC</col2>
</row>
<row>
<col1>C</col1>
<col2>ABC</col2>
</row>
</table>
When the transformation is performed on any XML document (not used), the wanted, correct result is produced:
<table>
<col2>ABC</col2>
----
<col2>ABC</col2>
----
<col2>ABC</col2>
----
</table>

Answer 2

I think I may have figured this out based on an answer provided on another post (https://groups.google.com/forum/?fromgroups#!topic/microsoft.public.xsl/i8FwJUD0r8U).
<xsl:variable name="cols" select=
"document('test2.xml')/table/row[current()/col1 = col1]/col2[not(. = ../preceding-sibling::*/col2[current()/col1 = ../col1])]"/>
This appears to select unique col2 values into $cols eliminating the need for the second variable.