further optimization

Change-Id: I2aa664993ec49cdd109c6e5fb539be92da263465
diff --git a/nkjp2korap.xsl b/nkjp2korap.xsl
index 64b65e1..4aae734 100644
--- a/nkjp2korap.xsl
+++ b/nkjp2korap.xsl
@@ -429,10 +429,7 @@
   
   <xsl:template match="tei:*" mode="struct">
     <xsl:variable name="offsets" as="xs:integer+">
-      <xsl:variable name="akku"
-        select="map:merge(tail(fn:accumulator-after('elem-offset-seq')), map {'duplicates': 'use-last'})"
-        as="map(xs:string,xs:integer+)"/>  <!--test later if the merger is really needed here, given how accus work-->
-      <xsl:sequence select="map:get($akku, string(@xml:id))"/>
+      <xsl:sequence select="map:get(fn:accumulator-after('elem-offset-seq')[last()], string(@xml:id))"/>
     </xsl:variable>
     
     <xsl:variable name="my_name" select="local-name()" as="xs:string"/>