My stylesheets have grown rather complicated, but let me try to narrow 
down the problem I'm having to this:
I (think I) need to apply-templates to all elements in a namespace 
except for one: cs:creator.  So I've tried this (and a ton of other 
options on the relevant templates:
	    <xsl:apply-templates 
select="$style-biblio/cs:reftype[(_at_)name='book']/cs:*[not(cs:creator)]">
              <xsl:with-param name="source" select="."/>
            </xsl:apply-templates>
.... but am ending up with output like this (note extra "H. Arendt"):
           <p class="bibref" id="two"><span class="creator">Arendt, H. 
</span><span class="title italic ">The Human Condition</span>, H. 
Arendt(<span class="year">1959</span>)<span class="origin"><span 
class="place">New York</span>:<span 
class="publisher">Doubleday</span></span>.</p>
To try to sum up in a nutshell:
I had a rather complex set of stylesheets that I am now making more 
complex by integrating processing based on a config file (in the cs 
namespace) that drives formatting of source data (in the mods 
namespace).
The problem is that I'm getting duplicate names processed because my 
main template does some funky grouping stuff with the creator names, 
and I don't understand how to not have the mods:mods/mods:name 
processed a second time, but insure that 
mods:mods/mods:relatedItem/mods:name does get processed.
I'll paste the main templates in the hope that it makes sense to 
someone!
<xsl:key name="bibref" match="mods:mods" use="@ID" />
<!-- take processed biblist and run templates on them in bib mode -->
<xsl:template 
match="mods:modsCollection[$citation-class='author-year']" 
mode="bibliography">
  <xsl:variable name="first" as="xs:boolean" select="position() = 1" />
  <xsl:variable name="author-name" select="bib:grouping-key(.)"/>
  <xsl:for-each-group select="mods:mods" group-by="bib:grouping-key(.)">
    <xsl:for-each select="current-group()">
      <xsl:variable name="first" as="xs:boolean" select="position() = 
1" />
      <p class="bibref" id="{(_at_)ID}">
        <xsl:value-of select="$bibref-before"/>
        <span class="creator">
          <xsl:choose>
            <xsl:when test="count(current-group()) = 1">
              <xsl:choose>
                <xsl:when test="not($first and position() = 1)">
                  <xsl:text>———.</xsl:text>
                </xsl:when>
                <xsl:otherwise>
                  <xsl:choose>
                    <xsl:when test="mods:name">
                      <xsl:apply-templates select="mods:name" mode="full">
                        <xsl:with-param name="sort-order"
                                select="$style-biblio/@author-as-sort-order" />
                      </xsl:apply-templates>
                    </xsl:when>
                    <xsl:otherwise>
                      <xsl:value-of select="mods:noname-substitute"/>
                    </xsl:otherwise>
                  </xsl:choose>
                </xsl:otherwise>
              </xsl:choose>
            </xsl:when>
            <xsl:otherwise>
              <xsl:choose>
                <xsl:when test="mods:name">
                  <xsl:apply-templates select="mods:name" mode="full"/>
                </xsl:when>
                <xsl:otherwise>
                  <xsl:value-of select="mods:noname-substitute"/>
                </xsl:otherwise>
              </xsl:choose>
            </xsl:otherwise>
          </xsl:choose>
        </span>
        <xsl:choose>
          <xsl:when test="mods:relatedItem/@type = 'host'">
            <xsl:variable name="issuance"
                          select="mods:relatedItem/mods:originInfo/mods:issuance" 
/>
            <xsl:choose>
              <xsl:when test="$issuance = 'continuing'">
		<xsl:apply-templates 
select="$style-biblio/cs:reftype[(_at_)name='article']/cs:*">
                  <xsl:with-param name="source" select="."/>
                </xsl:apply-templates>
              </xsl:when>
              <xsl:otherwise>
		<xsl:apply-templates 
select="$style-biblio/cs:reftype[(_at_)name='chapter']/cs:*">
                  <xsl:with-param name="source" select="."/>
                </xsl:apply-templates>
              </xsl:otherwise>
            </xsl:choose>
          </xsl:when>
          <xsl:otherwise>
	    <xsl:apply-templates 
select="$style-biblio/cs:reftype[(_at_)name='book']/cs:*">
              <xsl:with-param name="source" select="."/>
            </xsl:apply-templates>
          </xsl:otherwise>
        </xsl:choose>
        <xsl:value-of select="$bibref-after"/>
      </p>
    </xsl:for-each>
  </xsl:for-each-group>
</xsl:template>
cs: creator looks like:
<xsl:template match="cs:creator">
  <xsl:param name="source"/>
  <xsl:apply-templates>
    <xsl:with-param name="source" select="$source"/>
  </xsl:apply-templates>
</xsl:template>
.... and mods:name (in full mode):
<xsl:template match="mods:name" mode="full">
<!-- We have two modes for name processing. "Full" renders complete 
personal
names in bibliographies and footnote/endnote style ctiations, while
"short" renders just family name(s) commom in author-year citations. -->
  <xsl:param name="sort-order" select="first-author" />
  <xsl:param name="prefix"/>
  <xsl:param name="suffix"/>
  <xsl:value-of select="$prefix"/>
  <xsl:choose>
    <xsl:when test="$sort-order='first-author' and position() = 1 and 
not(parent::mods:relatedItem)">
      <xsl:apply-templates select="mods:namePart[(_at_)type='family'] | 
mods:namePart[not(@type)]"/>
      <xsl:text>, </xsl:text>
      <xsl:apply-templates select="mods:namePart[(_at_)type='given']"/>
    </xsl:when>
    <xsl:otherwise>
      <xsl:apply-templates select="mods:namePart[(_at_)type='given']"/>
      <xsl:apply-templates select="mods:namePart[(_at_)type='family'] | 
mods:namePart[not(@type)]"/>
    </xsl:otherwise>
  </xsl:choose>
  <xsl:choose>
    <xsl:when test="position() = last()" />
    <xsl:when test="position() = last() - 1"> and </xsl:when>
    <xsl:otherwise>, </xsl:otherwise>
  </xsl:choose>
  <xsl:value-of select="$suffix"/>
</xsl:template>
The source data that is the problem looks like this:
<mods>
  <name>
    ...
  </name>
  <relatedItem>
    <name>
      ...
    </name>
  </relatedItem>
</mods>
Bruce