I have 2 parallel ports. How do you read both? I guess 1 at a time?
Note that I said ONE OF my BOBs. I also have one of Peter Homann's new BOBs, but it does not have LEDs . . . . consequently it is very small . . . so advantages are traded. For two ports, you need two BOBs.
One exception I am aware of is a product called 'smooth stepper'. There is a section on this forum dedicated to the product. I don't know much about it, but apparently (among other advantages) it replaces two parallel ports with a USB connection.