Mine is USB, both were set to com 4(the correct port) and run at seperate times.
Even though one is run at a time, the very fact that the other exists (Wintest) stops the CC software from running. At least here it did, and for several other people.
By changing the com port to an incorrect one in Wintest, it should allow the CC software to work. I usually have Wintest on com 3 to work on the module then set it to com 1 when I use CC2. I only use Wintest for the 631 USB to set the boot screen. My 634 on virtual com 6 has its own bootscreen so no shenanigans there.
Just try it and let me know how you get on. It will protest but try it anyway. This used to happen on the 631 before I added the 634 and on CC1 software.