Merging 2 xml files

Hi friends,
I am new to xslt. I am facing a problem in merging 2 xml files into 1. I am suceeded in that but my next requirement is that duplicate rows should come only once. Can anyboy help me in removing in duplicates?
Here I am attaching the zip file which contains the files related to this one.

input : delivery.xml this file contains names of files to be merged(i.e a.xml and b.xml)
XSLT : merge.xsl
I am also enclosing the files to be merged(i.e a.xml and b.xml)

This is very urgent for me.

Thanks in advance.

Jithu
XSLT.zip (1.18 KB)