same prefix, different namespaces (URIs)

Hello,

I need/want to use the same prefix in the result document as in the source
document, but those prefixes need to be mapped to different URIs.

Sample for prefix 'nsn':

source document

<source xmlns="http://foo.org" xmlns:nsn="http://foo.org/1999">
  <nsn:data>hello</nsn:data>
</source>


result document

<source xmlns="http://foo.org" xmlns:nsn="http://foo.org/2009">
  <nsn:item>hello</nsn:item>
</source>


Is it possible (as shown here) to map the nsn:data element to nsn:item
element?

Thanks for your help.

Heiko