This error means the SSO endpoint corresponding to vc_#2 cannot be found by lookup service.
You can check what endpoints are available to lookup service by opening https://{vcaddress}/lookupservice/mob?moid=ServiceRegistration&method=List and invoking the method with empty <filterCriteria/> request body, then looking in the results for endpoints of type com.vmware.cis.cs.identity.websso
I suppose you need to have 2 endpoints of this type (one for each vc) in order for token validation logic to succeed.
