xsl sort - 1 transform or 2

I am trying to accomplish the following transform (using saxon 6.5.3) in 
the following order:
1. sort by "exchange", then sort by "sort" within exchange
2. where an "exchange" <> the previous "exchange"  I want to print above
"name":
@blockhead:"exchange"
@block:"name"
3. where a record's "symbol" is the same as the previous record's "symbol" 
only output the initial record's "symbol"
 
Everything works as hoped when the sort isn't applied, but when it is
applied 
I get the @blockhead/@block printing above the same name 
"Titanium..." and not above the name "AltaCda Enrg" as I was hoping. 
I also don't get a consolidation the the symbols. 
Do I have to do this in 2 stages - perform the sort as 1 xsl and then do 
the rest on the sorted xml output? or can I do it in a single style sheet?
 
Here's the xml
 
<?xml version="1.0" encoding="iso-8859-1"?>
 
<publication>
<document>
<record fragment="blocktrades">
<exchange>Toronto</exchange>
<name>Thomson</name>
<sort>Thomson Corporation 01TOC</sort>
<time>13:30</time>
<symbol>TOC</symbol>
</record>
<record fragment="blocktrades">
<exchange>Toronto</exchange>
<name>Abitibi-Cons</name>
<sort>Abitibi Consolidated Incorporated 01A</sort>
<time>11:25</time>
<symbol>A</symbol>
</record>
<record fragment="blocktrades">
<exchange>Toronto</exchange>
<name>Petro-Canada</name>
<sort>Petro Canada 01PCA</sort>
<time>13:27</time>
<symbol>PCA</symbol>
</record>
<record fragment="blocktrades">
<exchange>Toronto</exchange>
<name>Abitibi-Cons</name>
<sort>Abitibi Consolidated Incorporated 01A</sort>
<time>11:23</time>
<symbol>A</symbol>
</record>
<record fragment="blocktrades">
<exchange>TSX Venture</exchange>
<name>Titanium</name>
<sort>Titanium Corporation Incorporated 01TIC</sort>
<time>13:26</time>
<symbol>TIC</symbol>
</record>
<record fragment="blocktrades">
<exchange>TSX Venture</exchange>
<name>Omni-Lite</name>
<sort>Omni Lite Industries Canada Incorporated 01OML</sort>
<time>13:24</time>
<symbol>OML</symbol>
</record>
<record fragment="blocktrades">
<exchange>TSX Venture</exchange>
<name>AltaCda Enrg</name>
<sort>Altacanada Energy Corporation 01ANG</sort>
<time>11:59</time>
<symbol>ANG</symbol>
</record>
</document>
</publication>
 
Here's the xsl
 
<xsl:stylesheet
    version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 
<xsl:output
    method="text"
    encoding="iso-8859-1"
    indent="yes"/>
 

<xsl:variable name="tab" select="'&#009;'" />
<xsl:variable name="nl" select="'&#10;'" />
 

<xsl:template match="publication">
<xsl:for-each select="document">
  <xsl:for-each select="record">
    <xsl:sort select="exchange" order="ascending"/>
    <xsl:sort select="sort" order="ascending"/>
    <xsl:choose>
      <xsl:when test="position() = 1">
        <xsl:text>@blockhead:</xsl:text>
        <xsl:value-of select="exchange"/>
        <xsl:value-of select="$nl"/>
        <xsl:text>@block:</xsl:text>
        <xsl:apply-templates/>
      </xsl:when>
      <xsl:when test="exchange = preceding-sibling::record[1]/exchange">
        <xsl:value-of select="$nl"/>
        <xsl:apply-templates/>
      </xsl:when>
      <xsl:when test="exchange != preceding-sibling::record[1]/exchange">
        <xsl:value-of select="$nl"/>
        <xsl:text>@blockhead:</xsl:text>
        <xsl:value-of select="exchange"/>
        <xsl:value-of select="$nl"/>
        <xsl:text>@block:</xsl:text>
        <xsl:apply-templates/>
      </xsl:when>
    </xsl:choose>
  </xsl:for-each>
</xsl:for-each>
</xsl:template>
    
<xsl:template match="name">
  <xsl:value-of select="."/>
</xsl:template>
 
<xsl:template match="symbol">
  <xsl:choose>
    <xsl:when test=". = ../preceding-sibling::record[1]/symbol">
      <xsl:value-of select="$tab"/>
    </xsl:when>
    <xsl:otherwise>
      <xsl:value-of select="$tab"/>
      <xsl:value-of select="."/>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>
 
<xsl:template match="text()" />
</xsl:stylesheet>
 
Here's the current output:
 
@blockhead:Toronto
@block:Abitibi-Cons A
Abitibi-Cons A
Petro-Canada PCA
AltaCda Enrg ANG
Omni-Lite OML
@blockhead:TSX Venture
@block:Titanium TIC
 
and here's the desired output:
 
@blockhead:Toronto
@block:Abitibi-Cons A
Abitibi-Cons
Petro-Canada PCA
@blockhead:TSX Venture
@block:AltaCda Enrg ANG
Omni-Lite OML
Titanium TIC


And of course any help is greatly appreciated,
Dan