I listened to a little bit of this, and apparently the Fatima Center believes the real Sr Lucy remained alive for many years, or even decades, after the imposter appeared. This is bizarre and completely lacking in basis, since there is no known sighting or photograph or video of the real Sr. Lucy after the year 1958. But Fatima Center claims that, when the faker said something they agree with, such as that the consecration of Russia had not been fulfilled, that that was the real one talking, and when she would say something modernist, that that was the faker.
Not only is this contrary to all the evidence we have, but from an a priori perspective it is completely absurd. If one were going to eliminate someone and replace them with an imposter, they would have to eliminate the real person so they can't expose the imposture. What's the point of having a fake Sr Lucy if they always had to worry that the real one would simply tell people that there was a fake version of her out there? You have to eliminate the real person if you want to have an imposter. If you want to do it right, that is.