Want to print mutiple booklet copies of a pdf and stapled individually but copies are merged

Here is the code to print the document in mutliple copies sliently.

/* SilentPrint */
var pp = this.getPrintParams();
pp.NumCopies = global.numberOfCopies;
pp.interactive = pp.constants.interactionLevel.silent;
this.print(pp);

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Here is the code for me to put in the number of copies.

app.addMenuItem({ cName: "Set Batch Printing Copies", cParent: "File", cExec: "AskForPrintingCount();", nPos: 0 });

if (typeof global.numberOfCopies === 'undefined'){
global.numberOfCopies = 1;
global.setPersistent("numberOfCopies", true);
}

function AskForPrintingCount()
{
var response = parseInt(app.response("Number of copies to be printed", "Printing Count Setting", global.numberOfCopies));
if (!isNaN(response)){
if (response >= 1) {
if (response >= 500){
var largeAmountPrintingConfirmation = app.response("You are going to print " + response + " copies, Are you sure? (Y/N)" , "Confirmation", "N");
if (largeAmountPrintingConfirmation == "Y" || largeAmountPrintingConfirmation =="y"){
global.numberOfCopies = response;
}
} else {
global.numberOfCopies = response;
}
} else {
app.alert("You have entered " + response + ". The printing count is not changed." );
}
}
}

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The issue i am running into is that:

1. I can print pdf to say 5 copies booklet which is stapled individually.

2. My colleage failed to reproduce the same result using the same script, the same printer and the same setting. His result is a single copy of booklet. And 5 copies are merged together (The first page of the next copy is printed directly after the last page of the prior copy) and stapled together.

Can anyone give me some idea on what could be the issue here?