I tried trading Z1fx & Z2fx simultaneously with two Zorro instances on the same account, but it definitely doesn't work because I get Error 052: Broker interface busy when trying to start trading in the 2nd instance. Tested and can confirm this happens with both old & new (just released) FXCM.dll

I also have a lockup of the 2nd Zorro instance when doing WFA in it, while the first one is trading. It runs upto 6: 0482 (or so) and then freezes (stops responding). Have to kill it. And it is repeatable, always locks up at the same counter.