There are a lot of FIRMLY held opinions on this forum as to the proper way to carbonate your beverage of choice. With that in mind , a few questions, do you have a dual regulator? Are you patient enough to wait it out? If you have the dual regulator, leave the first at ten, and carb the second as you wish. If you have a single, I will guess(it is only a guess) you will over carbonate beer 1, and under carbonate beer 2. I would leave it at 10 or 12 psi until it is carbonated to your desired level. In the end it is your beer, and whatever you choose to do, you will learn something.