DuplicateTest fails when testing OOB multicast to all three senders

DuplicateTest does the following:

• creates three channels containing the DUPL layer called c1, c2, c3
• DUPL is used to duplicate messages sent
• channel receiver for channel each keeps a map of messages received from each sender
• channels send messages: regular, OOB, or mixed
• the test checks that the messages received by each channel are correct in number and in order

The test testOOBMuloticastToAll3Senders is failing regularly on multple platforms. The test makes each of the channels send OOB multicast messages to the group, but only two of three members ever end up receiving the multicast messages. Al example of the failure:

Error Message
expected size=3, msgs: [C2, C1]

Stacktrace
java.lang.AssertionError 
at org.jgroups.tests.DuplicateTest.check(DuplicateTest.java:217) 
at org.jgroups.tests.DuplicateTest.testOOBMulticastToAll3Senders(DuplicateTest.java:123)