The problem is that not just VVDI, all other tools except VCDS use genetic ftdi driver .
Problem come when you install one device with this driver , you cannot install other . Because Win7 do not know how to separate this driver between devices like Win XP.
Only Win XP can do this , separate this driver between devices.
I had same problem and had to find Laptop with Win XP. I install first SMOK which use same driver and after that I was not able to install VVDI or any other device with ftdi driver.
Only solution was is , to ,make own driver with own name , example “VVDI Driver installer” like VCDS did , but of course this cost money which no one want to inverts and spend money on this.