For some reason, the Integration MBeanExporterHelper is not preventing the standard context MBeanExporter from exporting the AbstractMessageRouter. This should be suppressed (when an IMBE is present) because it's annotated @IntegrationManagedResource.
Workaround in the stack overflow answer.
Could be an SI issue, but investigation needed. However, we should probably include the stream/job name in all MBeans for the stream (as is done for the integration exporter).