I heard some fairly detailed analysis on a podcast (SYSK) on the subject of name/date matches, and the "millions" of votes. Some macro-statisticians eliminated every variable, but finally couldn't fully explain ~20,000 exact matches of names and birthdates.
Until they saw an interesting pattern: The Autumn matches were all for folks born in the autumn.
Same for June, May, April, Holly, Noel, Summer, etc. The single most common match was a female with an Hispanic surname, born on March 19th. Another common match was an Irish surnamed boy, born on March 17th. I'm sure you can guess the first names.
That accounted for the last 20,000.
They also pointed out if 23 people are in the same room, the odds are 50-50 two people have the same birthdate.