What you are stating here would actually be against the Terms of Use, specifically the following section:
Eligibility.
You represent that you are an adult in your country of residence. You agree to these Terms of Use on behalf of yourself and, at your discretion, for one (1) minor child for whom you are a parent or guardian and whom you have authorized to play the Game using the license granted to you.
However, to answer your actual question, I do not believe that you would be able to log into both at the same time, because Blizzard limits the number of logins per Battle.net accounts to one (1). Additionally, it would be problematic, especially due to the recent addition of Real ID; which game would Battle.net report that your account is logged into (WoW or SC2)?
I will admit, though, that this is purely conjecture, and I cannot say for certain right now, because I have not attempted to log into both at the same time.