Exception #4 to 406.12(A), (B), &(C) says that you can install a non-TR two wire replacement receptacle where there is no EGC.
I assume that exception exists because no one makes a non-grounded TR receptacle.
That being said, I am not sure that I would do that. There is some danger to the kids in the day care, but then again, if they have two objects, there is no problem sticking the both in a TR receptacle and you don't have to do it at the same time.
Every time I go to a trade show where they have TRs on display, if there are two objects there, they will both be sticking out of the receptacle when I walk away.