Protecting?

Question
Hi, I have 2 guinea pigs, a black one and a white one.  Whenever I pick up the black one, the white one starts frantically whistling at me.  BUT when I pick up the white one the black one doesn't seem to care.  Could this be protecting or perhaps jealousy?  Also, they are both supposed to be male but could this behaviour signal that one is female? (I have only owned them for about 3 weeks)

Answer
Tracey,
  If you go to http://cavyspirit.com/sexing.htm you can tell whether your pig is a male or female. If they are both of the same sex then it mat be that the white one is trying to make friends but the black one has no interest in becoming buddies. If one is a male and the other female, then here are some helpful links.  http://cavyspirit.com/breeding.htm
http://www.cavymadness.com/careboysgirls.php#maturitybreeding