Yes, that is true from what we've seen in the past goals and what others have reported.
EDIT: Now that I've re-read your post again, I wanted to point out that if you want to master a certain recipe, you can. You just have to not serve the other recipe before you do so. For instance, if you want to master Boyish Pops, then when you get to part 3 of the side goal, just make sure you don't serve the 26th round of Pink Cupcakes until you finish mastering the Boyish Pops or vice versa. I hope I explained that in a way that's understandable, lol. If not, please feel free to ask for clarification or any follow up questions.