Hello
do you try this using the SDK (with C# or java code) or just tweaking the SOAP XML?
If it is the first case - I managed to submit with preserveIdentity set - it preserves "uuid" in target config spec but doesn't preserve "instanceUuid". This looks like a bug (though nobody seems to have hit it before). Is that your issue?
If you are trying to tweak the SOAP XML, then I'd recommend you start using the SDK ;-)
Regards,
Plamen