I have been installed Weblogic 10.3.6 with Sun JDK 1.6 on Windows 7 64 bit. This has worked great for a client sending in a soap request which is processed in my war as a 1.2 message. Debugging this shows the response is valid in my code, and works on Sun 1.6 fine.
When I switched to JRockit [jrockit-jdk1.6.0_33-R28.2.4-4.1.0-windows-x64] I started to receive a duplicate soap envelope and soap body wrapped around the valid soap envelope which worked before.
With the only change being switching to JRockit, this must be the cause of the addition of the duplicate the soap body and envelope. I searched this forum and Google and have not found a reason or solution.