I just put through a single test call and it generated 2 calls at the same time on lines 1 and 2. They are the very first calls in the log attached (search for 041).
I believe this may have been happening in previous versions as we have had reports previously but had been unable to replicate it until now.
The call in this instance was generated using an XML file, and I confirmed it was only 1 call meant to be going out. The two calls started 1 millisecond apart.
If you require any additional information please just let me know.