Or it's not Riddle at all. I was writing out a whack of reasons for this, but there is no need: Eliezer has spoken:

I've edited the birthdate of the person Amelia refers to, to be 1927 - too many people were interpreting that as "She thinks he's Tom Riddle" despite the House incongruence, an interpretation I'd honestly never thought of due to Illusion of Transparency.