you must be editing the upperarm of man2. while in the man2 movieclip you can use the properties panel to affect the upperarm of only man2 by single (not double) clicking the upperarm to select (not edit) it.
Thanks for your immensely speedy response but I seem to have given a bad example; UpperArm was supposed to indicate a complex MovieClip in itself.
I was trying to come up with an example where you might duplicate a complex symbol from the library which was built itself of smaller library symbols (and possibly they in turn of smaller symbols ad infinitum). If you have created a complicated object and wish to create a second copy you can use duplicate to get two versions of the complex symbol in the library. The lesser symbols, however, remain instances of a single class so any edits to them ripple through all duplicates.
My current question comes from writing a "Match the Question to the Answer" style exercise. I made myself a QandAMatch MovieClip which would have massive reuse value for me but since it is hierarchical in setup you have to clone a chain of 4 symbols for each edit which is not only tedious but also makes the library look like nothing on earth.
so, you've found that creating a copy of a movieclip does NOT create copies of all (or any) children. all movieclip copies share the same children. that's expected (and desirable) behavior.
what you want is to create instance copies, not object copies.
to do that either drag that library clip to the stage and then edit the instance's children or, use actionscript to create an instance (after assigning a class to the object) and use actionscript to edit the instance's children.