Seeking unidirectional control of two 12V motors with TB-6612FNG

Sparkfun Dual TB-6612FNG Breakout

Can the Sparkfun breakout of the TB-6612FNG dual motor driver be used to control 2 motors that will only spin in one direction and not the other? As this chip is an H bridge, I realize that it's true purpose is motor control of both directions, but I only needed unidirectional control for my project and my limited knowledge lead me to purchase 4 of these breakouts. I didn't yet test anything because bits bits of info I gather in other threads leads me to believe that because I only used a single input per channel (unidirectional), my Arduino may be opened to back EMF. Once again, my limited understanding leads me to believe that without a diode in place, possible over rotation of the motor after it is de-energized might push voltage and/or current back into the H bridge and possibly the Arduino. Some insight please?

The application is a hydroponics controller, this being specifically the 8 peristaltic pumps that will pump in nutrient concentrates into the system where and when my sketch determines. I purchased two 4 head modules (Jebao DP-4 and slave unit) and hacked the motors and mounting plates, and merged them into a single housing. There are also green LEDs conveniently located next to each dosing head that will later be incorporated, but right now I just want to get the motors safely turning at variable speeds. The motors are 12 volt and do not directly drive the dosing pump head. Instead the motor shaft is pressed between 3 free rolling cylinders and the contact is similar to a sprocket turning another sprocket. I don't yet know how this translates into how many revolutions equals a milliliter. Because there is no direct drive, I doubt there is much load on the motor, but the way it's pinched between the rollers, I can't imagine there would be any over rotation either. Still I don't want to risk any components and remain safe.

Any feedback?

leads me to believe that because I only used a single input per channel (unidirectional), my Arduino may be opened to back EMF.

Rubbish, you are mistaken.

The protection from back EMF that the chip uses as a H bridge is still in operation if you only ever use it to drive in one direction.
The one chip will control two motors. From what I can see of the data sheet it is not possible to drive four motors per chip like it is when a chip is arranged as four half bridges.

Awesome! Thanks Mike!