Consider the following scenario:
You install Cumulative Update 6 (CU6) for Microsoft BizTalk Server 2010 on a BizTalk server.
You publish an orchestration as a web service that uses a two-way solicit-response WCF port (WCF custom binding).
You configure the source of the incoming BizTalk message body to use Path with the following string in the WCF send port:
/*[local-name()='Fault']/*[local-name()='detail']/* | /*[not(local-name()='Fault')]
Messages are sent to the web service at the same time by several orchestration instances.
In this scenario, some orchestration instances receive the same response body of other orchestration instances.
Cumulative update information
This issue was first fixed in the following cumulative update of BizTalk Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.