How to Filter duplicate combination of XML tags

Question

I've a question depending on xml files. Below is an example of my xml code. What I want to filter is the following: The tag value 'csvconstituentPartNumber' may only appear once in combination with the tag value 'csvassemblyPartNumber'. So it does not mean that 'csvconstituentPartNumber' may not appear more than once in the complete file, but not in combination with the value of 'csvassemblyPartNumber'.

In the code is an example: block 1 has the combination of 'csvassemblyPartNumber' 0000006710 with 'csvconstituentPartNumber' 0000001399. This comdination 0000006710 with 0000001399 may only appear once in the hole XML file. Block 2 and 3 contains the same combination of tag values. 'csvassemblyPartNumber' 0000006710 with 'csvconstituentPartNumber' 0000001537. This is not allowed. So I'm searching for a xsl code that finds those duplicate combinations and that I can run in an Internet Explorer.

Hopefully someone can help me!

<?xml version="1.0" ?><!DOCTYPE NmLoader SYSTEM "standardX24.dtd">
<NmLoader>

<csvBeginOccurrencedAssemblyAdd handler="wt.part.LoadPart.beginOccurrencedAssemblyAdd" >
<csvassemblyPartNumber>0000006710</csvassemblyPartNumber>
<csvassemblyPartVersion>A</csvassemblyPartVersion>
<csvconstituentPartNumber>0000001399</csvconstituentPartNumber>
<csvconstituentPartQty>0.7100000</csvconstituentPartQty>
<csvconstituentPartUnit>m</csvconstituentPartUnit>
</csvBeginOccurrencedAssemblyAdd>
<csvEndOccurrencedAssemblyAdd handler="wt.part.LoadPart.endOccurrencedAssemblyAdd"/>

<csvBeginOccurrencedAssemblyAdd handler="wt.part.LoadPart.beginOccurrencedAssemblyAdd" >
<csvassemblyPartNumber>0000006710</csvassemblyPartNumber>
<csvassemblyPartVersion>A</csvassemblyPartVersion>
<csvconstituentPartNumber>0000001537</csvconstituentPartNumber>
<csvconstituentPartQty>1</csvconstituentPartQty>
<csvconstituentPartUnit>ea</csvconstituentPartUnit>
</csvBeginOccurrencedAssemblyAdd>
<csvEndOccurrencedAssemblyAdd handler="wt.part.LoadPart.endOccurrencedAssemblyAdd"/>

<csvBeginOccurrencedAssemblyAdd handler="wt.part.LoadPart.beginOccurrencedAssemblyAdd" >
<csvassemblyPartNumber>0000006710</csvassemblyPartNumber>
<csvassemblyPartVersion>A</csvassemblyPartVersion>
<csvconstituentPartNumber>0000001537</csvconstituentPartNumber>
<csvconstituentPartQty>5</csvconstituentPartQty>
<csvconstituentPartUnit>m</csvconstituentPartUnit>
</csvBeginOccurrencedAssemblyAdd>
<csvEndOccurrencedAssemblyAdd handler="wt.part.LoadPart.endOccurrencedAssemblyAdd"/>

</NmLoader>