problem in duplicatingMovieClip in action script2

I am creating a flash project for my exam. Actually I am new in flash and am using action script2.

I am having a movieclip having instance name "a_mc" which is a rotating rectangle around 360degree. The action I have given for this "a_mc" is
n=1
while(n<5)
{
duplicateMovieClip("a_mc","a_mc"+n,2);
setProperty("a_mc"+n,_rotation,random(360));
setProperty("a_mc"+n,_alpha,(70));
n++;
}

This is working.
But I want to make another movieclip named as "b_mc" where there shall be duplicates of "a_mc" multiplied by 5 times but I am failing to do it.
Can anyone please help me to sort out it.

Thanks to all of you.
Regards.

I guess I dont fully get what your asking..??

but wouldnt the same code work?

actionscript Code:

e=1;
while(e<5){
     duplicateMovieClip("a_mc","b_mc"+e,2);
     setProperty("b_mc"+e,_rotation,random(360));
     setProperty("b_mc"+e,_alpha,(70));
     e++;
}