exploding mulitvalued files makes nodes duplicate

Problem/Motivation

using the explode plugin on multivalued files to import in a media ref field makes nodes duplicates.

I am using feeds with the xml parser provided by feeds extensible parser.
my xml files looks like:

<node>
<docs>file-sample_150kb.pdf; test.pdf</docs>
  </node>

The same plugin does work well for taxo ref field