Load movies Iinto and empty MC

Hi, there all!

I have a question for all of you ActionScripters heroes!!!

I have an empty movie clip which I use to load movies into it…(A) and (B)…

My question is:
If I load movie “A”, and later on I load “B” (here is my quesion) what happen to the loading process if I need to load “A” again? is goint to load it from scratch or some how stays in the cache?..