As I was looking for a video of "Officially Missing You" by Tamia on Youtube, I found this video and I was very amazed by how these girls sing and play.
Here's their another video singing "Nobody" by Wondergirls. I don't like this song, but after hearing their version, I'm starting to love it.
They're only 23 years old, and yes, they're twins. Both their parents are Koreans but they were raised in Sydney, Australia. Find more about them on their Youtube Channel.