http://blog.dedrickwelch.com/2009/01/obamas-twin-mexican-brother.html FAIL. He's from INDONESIA, not MEXICO: http://www.indonesiamatters.com/1472/ilham-anas/
have you seen his birth certificate to make sure he's really Mexican. That stuff is important I hear.
After some research. Sorry he's Indonesian. http://www.reuters.com/article/idUSTRE50H0BZ20090118 Never mind just saw your edit.
"They are generally regarded as harbingers of bad luck. In some traditions, a doppelgänger seen by a person's friends or relatives portends illness or danger, while seeing one's own doppelgänger is an omen of death."- wiki