Is it possible to cut a breadboard?
I would not recommend the cutting of the breadboard. To do so you end up losing the ability to plug in IC chips and components that have two rows of pins. Components of this type are typically plugged in across the center gap that I've identified by the yellow line in the picture below. 



There are plenty of sources that sell these breadboards at competitive prices that you would really be better off purchasing an additional board if you need two.