I agree with Jason. While you certainly CAN change around, there is no need to, and in fact, it might be a headache as maybe the change will affect the dynamics of your shooting.
I personally won't worry so much about how many bevels my broadheads have. I typically have no problem with penetration on the game I hunt using what I use.
Although Dr Ashby's studies are right-on and very informative, don't forget that two bevel heads have been taking game very well for a long long time and do not all of a sudden pale in the face of anything else.
Keep it reasonable, keep it sharp, and keep it in the RIGHT kill zone and you shouldn't have problems at all.
ChuckC