This sounds like a bug, so if can add the test case to remoting testsuite and open a jira issue, I'll look at it.
Remoting detection is actually pretty simple in implementation. Every few seconds (or whatever the heartbeat period is set for), a detector will emit its detection message (which contains an array of the invokers it sees locally at that point in time). The detector that receives this detection message will check its internal list of detection messages and check to see if the hash of the previous detection message is different from the one it just got. If so, will tell the NetworkRegistry that an update has occured (which then emits the UPDATED notification). The hash is calculated by simply adding the hash codes of all the invokers in they array within the detection message.
My guess there is a problem within calculating the hash in this case.