I'm not sure others have noticed https://issues.apache.org/jira/browse/SOLR-16013. I wanted to get some more eyes on this issue.
Basically what's happening is one ADDREPLICA command is creating two replicas. This happens in parallel tests that tear down the overseer leader in one test, while another test is firing ADDREPLICA requests in another test. In this situation the overseer leader being scaled down executes the ADDREPLICA and then the newly elected overseer executes the same ADDREPLICA. Joel Bernstein http://joelsolr.blogspot.com/
