Removal of duplicates from XSLT nodes

Below the XML which has duplicate values at node 1 and node 3.

<document>
<item>
    <ID>1000909090</ID>
    <flex>
        <attrGroupMany name="pageinfo">
            <row>
                <attr name="pagelength">10</attr>
                <attr name="pagewidth">20</attr>
                <attr name="pageheight">30</attr>
            </row>
            <row>
                <attr name="pagelength">50</attr>
                <attr name="pagewidth">60</attr>
                <attr name="pageheight">70</attr>
            </row>
            <row>
                <attr name="pagelength">10</attr>
                <attr name="pagewidth">20</attr>
                <attr name="pageheight">30</attr>
            </row>
        </attrGroupMany>
    </flex>
</item>
</document>

The output should not be having duplicate and the output XML should be in the below format

<?xml version="1.0" encoding="UTF-8"?>
<pagedetails>
<pagedata>
    <Relationship>
        <RelationType>PAGEDETAILSINFO</RelationType>
        <RelatedItems count="2">
            <RelatedItem referenceKey="PAGEDETAILSINFO-1000909090-10-20-30" />
            <RelatedItem referenceKey="PAGEDETAILSINFO-1000909090-50-60-70" />              
        </RelatedItems>
    </Relationship>
</pagedata>
</pagedetails>