A variable passed on to a template is tampered with - xslt

Question

<xsl:param name="currentPage"/>
<xsl:param name="group-size" select="'2'" />
<xsl:template match="/">
<xsl:variable name="userBlogSource" select="umbraco.library:GetXmlNodeById(umbraco.library:GetDictionaryItem('WeblogNode'))/node [string(data [#alias='umbracoNaviHide']) != '1' and data[#alias='author'] = $currentPage/#id]" />
<xsl:for-each select="$userBlogSource">
<xsl:sort select="data[#alias='dato']" order="descending" />
</xsl:for-each>
<xsl:if test="count($userBlogSource) > 0">
<h3><xsl:value-of select="umbraco.library:GetDictionaryItem('BlogpostsWrittenBy')"/> <xsl:value-of select="$currentPage/#nodeName" />:</h3>
<xsl:apply-templates select="$userBlogSource[(position() mod $group-size) = 1]" />
<ul>
<xsl:for-each select="$userBlogSource">
<li>
<a rel="bookmark" href="{umbraco.library:NiceUrl(#id)}" title="{#nodeName}">
<xsl:value-of select="#nodeName" />
</a>
</li>
</xsl:for-each>
</ul>
</xsl:if>
</xsl:template>
<xsl:template match="node">
<xsl:variable name="postnum" select="position()" />
<div class="weblog-posts-wrap">
<ul>
<xsl:for-each select=". | following-sibling::node[position() < $group-size]">
<li>
<a rel="bookmark" href="{umbraco.library:NiceUrl(#id)}" title="{#nodeName}">
<xsl:value-of select="#nodeName" />
</a>
</li>
</xsl:for-each>
</ul>
</div>
</xsl:template>
When I check the count of $userBlogSource it contains three elements. When I attempt to print the in a regular XSLT for loop it does print the correct elements. But when the variable is passed to the second template matching node, the content is suddenly different. Instead of the three nodes it should contain, it contains 4 nodes by entirely different authors.
Any idea of what I may be doing wrong?