Interestingly enough, I live in the Midwest and have still only heard it pronounced MEH-gin. I have a couple friends with the name and they both pronounce it that way.
Now that you say that, I actually pronounce both syllables of
Megan really fast?? It's very strange. I pronounce
Morgan much more slowly and I'm not sure why.
The pronunciations are different enough that my dad and I had a mini argument about it, LOL.