import in Protege failure

[David Makovoz]

I have the following in my ontology file:

  <rdf:Description rdf:about="http://www.aciedge.com/ontologies/cg.owl";>
    <owl:imports 
rdf:resource="http://www.aciedge.com/ontologies/multiResolutionalBayesian.ow
l"/>
    <owl:versionIRI 
rdf:resource="http://www.aciedge.com/ontologies/cg.owl"/>
    <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#Ontology"/>
  </rdf:Description>

When I try to open it in Protege, I get the following error
Ontology already exists. 
<http://www.aciedge.com/ontologies/multiResolutionalBayesian.owl>

When I replace the above with seemingly equivalent

    <owl:Ontology rdf:about="http://www.aciedge.com/ontologies/cg.owl";>
        <owl:versionIRI 
rdf:resource="http://www.aciedge.com/ontologies/cg.owl"/>
        <owl:imports 
rdf:resource="http://www.aciedge.com/ontologies/multiResolutionalBayesian.ow
l"/>
    </owl:Ontology>

everything works fine. 

What am I missing?

Thank you, 

David