Possibly the 6 and 4 were just transposed somewhere along the way. Pretty soon those sorts of errors become "fact."

That is sort of like the misinformation about the birthdate of Annette Hanshaw which was mistakenly listed somewhere as 1910 instead of the correct 1901.   Later articles were appearing commenting on what a remarkable singer she was for a teenager. Actually, she was a remarkable singer no matter what the age, but that is another story.