Warning Shibboleth.PropertySet : load() skipping duplicate property set:

When restarting shibd (2.5.0) I am encountering this warning:
"Shibboleth.PropertySet : load() skipping duplicate property set: {urn:eu:stork:names:tc:STORK:1.0:assertion}RequestedAttribute"

The session initiator looks like this:

<SessionInitiator type="SAML2" Location="/Login" forceAuthn="true" isPassive="false">
<samlp:AuthnRequest
xmlns:stork="urn:eu:stork:names:tc:STORK:1.0:assertion"
xmlns:storkp="urn:eu:stork:names:tc:STORK:1.0:protocol"
ID="_Meaningslessstring4xmlvalidatioN" IssueInstant="1900-01-01T00:00:00Z" Version="2.0">
<samlp:Extensions>
<storkp:RequestedAttributes>
<stork:RequestedAttribute Name="http://www.stork.gov.eu/1.0/eIdentifier" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri" isRequired="true"/>
<stork:RequestedAttribute Name="http://www.stork.gov.eu/1.0/givenName" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri" />
</storkp:RequestedAttributes>
</samlp:Extensions>
</samlp:AuthnRequest>

If I remove one of the 2 stork:RequestedAttribute elements, the warning goes away. It does, however, produce the expected AuthnRequest.