XML to XML using XSLT remove duplicates - xslt

Question

Below is an input xml file:
<assets>
<item>
<file_name>file123</file_name>
<description>testing</description>
<created>date</created>
<metadata>
<guest>name</guest>
<webinfo>test</webinfo>
<albumorder>3</albumorder>
<albumorder>3</albumorder>
</metadata>
</item>
</assets>
From the above xml metadata/albumorder is having duplicate. I want to keep only one albumorder element. How to remove the duplicate elements.
Result file should be like:
<assets>
<item>
<file_name>file123</file_name>
<description>testing</description>
<created>date</created>
<metadata>
<guest>name</guest>
<webinfo>test</webinfo>
<albumorder>3</albumorder>
</metadata>
</item>
</assets>

Answer 1

The following copies only elements, which don't have a same named preceeding sibling element:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="*">
<xsl:if test="not(preceding-sibling::*[name(.) = name(current())])">
<xsl:copy><xsl:apply-templates/></xsl:copy>
</xsl:if>
</xsl:template>
</xsl:stylesheet>

Answer 2

There is pattern called "XSL identity template" or "XSL identity transformation", that will keep all XML except for rules you define to change certain elements.
kiwiwings already pointed out the solution, I would just integrate it in the identity template, otherwise you would loose XML comments, attributes, and processing instructions (none of them are present in your XML, but someone else may have them).
<xsl:output method="xml" indent="yes" encoding="UTF-8"/>
<xsl:template match="comment()|processing-instruction()|text()">
<xsl:copy/>
</xsl:template>
<xsl:template match="*">
<xsl:if test="not(preceding-sibling::*[name(.) = name(current())])">
<xsl:copy>
<xsl:copy-of select="#*"/>
<xsl:apply-templates select="comment()|processing-instruction()|text()|*"/>
</xsl:copy>
</xsl:if>
</xsl:template>