Multi occurrences of the same predicate to the same object

Hi all,

I have a question about multi occurrences of the same predicate to the same
object 
(resource or literal). RDF syntax does not say anything about that. 
For example (DS:CreatedBy):

<?xml version="1.0"?>
<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:DC="http://purl.org/metadata/dublin_core/"
     xmlns:DS="http://www.w3.org/Schemas/DS-Schema/">
  <Description ID="Statement_001">
    <DC:Creator>John Smith</DC:Creator>
  </Description>
  <Description about="#Statement_001">
    <DS:CreatedOn>1998-02-06T14:00Z</DS:CreatedOn>
    <DS:CreatedBy>Jane Cooper</DS:CreatedBy>
    <DS:CreatedBy>Jane Cooper</DS:CreatedBy>
  </Description>
</RDF>

How should a RDF parser handle this? Should the multi occurrences be added
to the graph or skipped? 

TIA,
Alex