Multiple headers with name 'Action' and namespace found

[spica...@gmail.com]

Hi - I am trying to add soap header to service request within orchestration.
When i push message using SoapUI with soap header, it fails on WCF-BasicHttp send port while consuming another service.

Here is what i am doing in message assignment shape to set header:

outgoing_msg = incoming_msg;
outgoing_msg(WCFOutboundCustomHeaders) = incoming_msg(WCF.InboundHeaders);

Here is error;
Details:"System.ServiceModel.MEssageHeaderException: Multiple headers with name 'Action' and namespace 'http://some-namespace' found."

Per documentation, setting soap header seems simple but i could not get ride of this error.

Thoughts ???