Big prob about rmoving MC

look at my attachment and you will see that it creates 10 little pieces of ammo. When u click on the background it should delete one of those movie clips. But it deletes 2 of them. the code for creating is on the first layer and the deleting is on the background button symbol(click on the background to find it if you don’t know what im talking about).
create code

 _global.ammo = 1;
while (_global.ammo<=10) {
duplicateMovieClip(_root.ammo, 'ammo'+_global.ammo, _global.ammo);
_root['ammo'+_global.ammo]._x = 100+(10*_global.ammo);
_root['ammo'+_global.ammo]._y = 50;

destroy code(cut out to fit, its norm. in a button with on(press) thing)