Cheating at Chicken Shop!

I just had been to a chicken store nearby. Two girls already were ready to buy. The employee at this shop weighed the chicken in front of these & placed it on a wooden plank that he uses to cut this chicken into small pieces.There were big egg crates placed in front of the plank in such a way that it would block customers view.
This employee being mischievous while cutting these pieces pushed two small pieces behind the wooden plank.