Comment #13 on issue 2354 by jean.deruelle: B2buaHelper.createResponseToOriginalRequest() does not set different To tag to created response.
http://code.google.com/p/mobicents/issues/detail?id=2354
It doesn't disallow forking through proxy, and the RFC mention that a UAC should be able to cope with forked responses. But it doesn't mention being able to send multiple 2xx with different To Tags from the same UAS.
proxy forking is allowed only statelessly AFAIK. In our case there is transactions and dialogs
