I've seen Jessica misspelled as Jesica. A long time ago, one of my classmates spelled one of our other classmate's names like Kimbrilly or something way off (her name was Kimberly), but we were still in elementary school, so I'll cut him a break there.
Yeah, when I was in elementary school I was still on the "Wait, why is it SHAWN when it looks like SEEN?" page :) I think a lot of people leave out double letters accidentally. I get "Ema" way more often than I'd expect.
Oh really, I've never had my name spelled Ema (thank goodness!)And I do agree with you about Sean. Especially with Sean Bean - it looks like it should rhyme!