Hi there! That's awesome that you're loving both Shakeology and P90X! Both really are great!
In my opinion, I don't see anything wrong with having two shakes as day, as long as you're still hitting your daily calorie requirements (not being too restrictive, especially in combination with P90X) and feel you have enough energy. My daily intake ranges from 1800-2000 cal and there's lots of days where I'll have two shakes; I always have one post-workout for breakfast but will also sometimes have one as an afternoon snack or as "dessert" after dinner if I'm still feeling hungry.
Hope this helps a little!
-Kelly