Hello,

I hope you are doing fine, There is nothing called legal or illegal in studying. You can study as much as you want and whatever you want because it depends on you ultimately if you can simultaneously study two courses together. The timelines of both the courses might crash sometimes so you will have to take care of that. You can submit whichever certificate you please to.

I hope you find this information helpful. I wish you all the best for your future.

Good Luck