Duplicate coins

Ok, i’m thinking of starting to do a little platformer based on this:

 

http://www.gotoandplay.it/_articles/2004/04/platform.php


Now in that example the apples are seperate movieclips, but if i were to have many more on stage it wold really slow flash down, so i will need to attach movie or duplicate movie.
Now I’m unsure of this, so does anyone have any helpful sites or anything that would help me. I’d like for the coins to be placed in certain areas so the code will need to put a coin in a certain position.
Could anyone please possibly help me out in anyway, it would be great if someone could explain a little code to me.

Thank you.