Seems like it’s the night for a braindump over the last couple of weeks…..
Hotfix 923632 will do the job.
Also
be sure to follow these steps after applying hotfix 923632:
1. Open regedit and go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\BTSSvc$<HostName>
Make sure host name is the name of the BizTalk host which is publishing messages which
are routed to multiple req/resp subscribers.
2. At that key, add the DWORD value AllowMultipleResponses and set it to a value
of 1.
3.
Restart the host service after making this change.