Ah... this is a much nicer view of the logs! Nice one Praveen.
I thought about it and have no further ideas on this, and then suddenly I remembered that I have never used the RRB/ROB beans on a SOAP receiver that used XI 3.0 protocol.
From the error message, it generally means that the message that is in error has a message ID that already exists in the PI system. Other adapter types do not transfer message ID information, as it is only available in the header of the SOAP XI 3.0 protocol.
I'm not sure if the SOAP XI3.0 channel supports Async-Sync bridge. Of course, that still do not explain why it works from RWB but not end to end.
I don't have any existing sync proxy interfaces to test this out though.