Hi and welcome to the forums!
If your PC has USB, you can attach several external CD drives. You can even install a USB card to add more USB ports.
However, I think your biggest problem will be that you overload your hard drive. It can only write data so fast, no matter how many drives you are reading from. Actually, do several copies to your drive at once might be slower in the long run. This is because the hard drive heads will be moving all over the place to find empty space for each file it is trying to write.