I realize that you’re referring to traditionally-typed text, but Monotype was recently commissioned to design a typeface for the illustrator of Roald Dahl’s books, and they did indeed include alternates for each letter (along with variations in kerning):

>…He selected four subtly different alternates for each character that, combined, would make the text look random enough to look authentic while keeping the glyph set manageable

Article: http://www.monotype.com/expertise/case-studies/a-bespoke-han...

Visual comparison of the alternates: http://www.monotype.com/media/1837/quentin-alternates2.png