I'm not sure what you are trying to accomplish with a beige paired with a white. Like Alli said, it's a mute to mute pairing, and that is definitely not a step in the right direction to improving the breed per se. Just because both chins were shown and had good comments does not mean they should necessarily be bred together. The chins should complement each other, and should have few flaws (if any). Which by the way, there isn't a best in breed award for chinchillas, or a best in show--its called grand show. Which show were they shown at?
ETA: darn tabs, you type faster than me =p