There are, in fact, more than ten look-alikes of famous actors and models among adult performers. Some of the porn actors (and especially actresses) are naturally alike to the celebrity, and just make the benefit of their real faces. However, other adult performers who have at least the smallest chance to look similar or very much like one of the top celebrities, do plastic surgery immediately.
They work in different niches, so there are no chances for a porn star to later replace the celebrity in terms of popularity. However, within the adult entertainment industry, the demand for “celebrity” faces is huge. The thing is, celebrity has fans, some of them are very passionate ones. Celebrity’s fans look for sex videos with girls that would remind them of their big but unreachable love. So, the porn model with similar appearance will be very popular.