Seems to differ down ethnic lines. Lots of black guys have both pierced. Currently, most white guys I've seen with an earring are either PWT or have caught the ghey. Don't see them on Latino or Asian guys much, except for the want to be/gangbanger kids.
The first dude ever (who wasn't a drag queen) to have two earings:
The one in the front
Prior to GM, straight dudes wore one in the left, gay dudes wore one in the right and transvestites wore them in both. Call me old fashioned, but I still think the old rules apply. LT smokes a big pole.