I am confused about what you are looking for. You are setting the text to encode three different times, and generating two separate images, although you only save the last one to a file. That last one has a fixed string ("CODE 128") so you should be getting the same .png file each time.

Here's some quick-n-dirty code that produces three barcodes with different integer texts, hope it can help you.

#/usr/bin/perl

use strict;
use warnings;
use diagnostics;

use Barcode::Code128;

my $times = 3;
print "Running Barcode... encoding $times random integers\n";

my $object = Barcode::Code128->new();
$object->code('A');     # Enforce 128A?

srand(0);   # More interested in repeatability than randomness

foreach (1 .. $times)
{
    my $text = "";
    # Make up a 10-digit decimal number
    $text .= "".int(rand(10)) foreach (1 .. 10);

    my $filename = "code128_".$_.".png";
    open(my $png, ">", $filename) || die("Cannnot open $filename: $!")
+;
    binmode($png);
    print $png $object->png($text);
    close($png);

    print "Text \"$text\" encoded in file $filename\n";
}
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