I haven't seen this book so I can't say.
But one thing I have thought about in the cases of claimants and people saying they look like them when others say they don't is, I think that the power of suggestion is a big thing. If no one said, this is Alexei or Anastasia, and you were asked to say which historical figure the person resembled, you might not name a Romanov. But when someone says, this is so n so, it kind of takes our minds in that direction, and people are more likely to go, oh yes, I see it!
For example, take the backward masking in songs. There was a lot of flak years ago about people claiming there were evil messages in Led Zeppelin songs. Then I saw a guy on TV set out to prove a point, and he did- he played the record backwards for one group of people, telling them they were supposed to hear "here's to our sweet satan" and the people all gasped and said, oh yes, they heard that! How scary! Then he played the same part of the same song backwards for another group of people and did not tell them what the message allegedly was. They all said it sounded like gobbledegook, or some foreign language. No one suggested what it was supposed to be, and since it wasn't really there, they didn't hear it. It's no offense to anyone who sees and hears things because of the power of suggestion, it's part of the way the mind works. But it is a factor in these stories, I think.