Copy (NOT dublicating) af Movieclip?

I have a question, that i have thought about for a long time.

It has often been a pain in the *** evey time i had to copy a movieclip ex. 40 times, and then change an image in every movieclip. Beacus i had to break every mc apart, and build it manually again, because if i copy it 40 times, and chance something in one of the MCs, it change in every one of them.

So my question is:

Hov do i copy a mc (Or another item), so i can change something in it, without changing the same thing in every single copy?