I wouldn't be troubling yourself with how they figure out if a marriage certificate is real or fake. As long as yours is real, you have nothing to worry about. Spend your energy elsewhere.
All i care is that those offices i am dealing with only require photocopies and certified translation.
So i kind hope it would be the case for other people.
By the way, are you talking to me or samir44? ha ha I was like....hmm..uhhh..oooh...what? haha