Nonuniqueness of the p.d.f.
If a random variable X has a continuous distribution, then Pr(x=x)=0 for every individual value x. Because of property, the values of each p.d.f. can be changed at a finite number of points, or even at an infinite sequence of points, without changing the value of the integral of the p.d.f. over any subset a. In other words, the values of the p.d.f. of a random variable X can be changed arbitrarily at an infinite sequence of points without affecting any probabilities involving x, that is, without affecting the probability distribution of X.