It's very unlikely, but not impossible.

Superfecundation

Superfecundation occurs when fraternal twins have different fathers. These twins are the most disparate genetically, since they are, in essence, "half-siblings" to one another. In this type of twinning, a woman releases two eggs, each of which are fertilized by a different man's sperm. In the early 1900's, such a case occurred when an African-American woman gave birth to twins--one African-American, one mixed-race. She affirmed that she had two lovers--one African-American, the other white.

http://www.bellaonline.com/articles/art328 72.asp

actually I think that's what happened to my friend, plus we think the boy was a month smaller than the girl (I know, lucky on the gender thing). If you look at them, they both look like their mother, but definitely different in some aspects.

fraternal twins can have 2 different fathers

identical twings have the exact DNA and can not have 2 diff dads.

plus identical twins obviously are the same gender... that's why you never see conjoined twins with one being boy and the other girl (sry, conjoined twins just intrigue me so much)

actually there have been extremely rare cases where identical twins have come out different gender. however it has to do with a chromosomal defect. rarely rarely ever happens though

Wow..I never knew that twins could have 2 different fathers....hmmm...learn something new every day!! Haha!

they cant have different fathers if you have two eggs there they are both getting fertizled at the same time a drop of the mans juices have millions of sperms even if you were to have sex with another in a hour those eggs are already fertizled. As far as different color babies its all in the genes, a black woman and a white man had twins and one was black and one was white. And fratnel twins dont have to look alike they are just like any other brother or sister just born at the same time