I was just surfing around on the internet and I found this picture of Sora and he's holding Mickey's Keyblade? Now why would he be using his? Or holding it for that matter??? Here's the link, and you can tell that the Keyblade in Sora's Left arm, is clearly the gold one.
http://www.cf-network.com/cfan/IMG/jpg/P1060025b.jpg
http://www.cf-network.com/cfan/IMG/jpg/P1060025b.jpg