Rather than just looking at the features, it might help to look at each child's expression. Then what is thought to be Olga, appears more as Olga and what is said to be Tatiana, appears more to be so. Art is not photos and sometimes the artist changes features a bit. They would not do Olga's childhood forehead in all it's glory! lol! But that pleading expression is characteristic of Olga as a child AND characteristic of newspaper drawing I have seen of her from round this time ...also I can see a typical Tatiana expression ( her eyebrows were very expressive! ) in the other.