Multiple <wsse:Security> entry in SOAP 1.1 header

[javaduke]

I am currently using the WS-Security for SOAP 1.1 messages, and there is an option to add <wsse:Securty> tag to the header like this:

<S:Envelope xmlns:S="http://schemas.xmlsoap.org/soap/envelope/">
<S:Header>
<wsse:Security
xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
S:actor="...the URI comes here..."
S:mustUnderstand="1">
</wsse:Security>
</S:Header>
<S:Body>
<document
xmlns="....schema/v3"
recipientOrganization="TestOrg"/>
</S:Body>
</S:Envelope>

I read that there is an another option to define multiple Security tags in the Soap header but this seems to me a little bit senseless, because:

I know so that the <s:actor> defines the ultimate endpoint of the soap message.
So if there is a second Security block than is it possible to give to the header an another ultimate endpoint as well? Could somebody lightening me up, why such definition is possible, and what is the meaning of this?
Thank you in advance,
Bruce