Yes but they are expensive and you would need to upgrade both at the same time or only use one processor. You won't see prices fall below Intel's tray price for new processors. These are currently (each):
Just return it. Tell them you want to chage it for a 2.93GHz model and they will be happy to oblige. Two 2.93GHz processors are going to cost you ~$3,400 and you will likely void your warranty.