Having dual GPUs varies results depending on the system, ie: processor has few PCIe lanes, so usually 1st slot (nearest CPU) will be X16 while second will be X8, in this case there is a performance issue, unless the processor is able to more than 32 PCIe lanes and if the mobo allows it, you would have X16 on 1st and 2nd slots, the latest Threadripper processors with 64 PCIe you would have X16 on the four slots, if the mobo has that amount.
Im looking forward to see the fixes as soon the preview 1 is ready for download.