If there are only two zeroes and no duplicates, the polynomial is a quadratic expression: f(x)=x(x-8)=x^2-8x=0. If we duplicate a zero, for example x=8, the polynomial becomes f(x)=(x^2-8x)(x-8)=x^3-16x^2+64x with zeroes at 0 and 8, but 8 is repeated.