Functional mushrooms are known to work synergistically, meaning they may accomplish more together than alone. You can certainly stack different mushroom extracts together. In fact, many people do, including us here at FreshCap.
As with any natural supplement, everyone will respond differently so it is best to listen to your body when looking for the right dose. We typically recommend 1-3 grams of mushrooms per day. You can start by taking half a serving of each and see how you feel. Many people will take 2 full servings per day, but see what works best for you.