Ok, those duplicates were actually Chart::Mountain trying to be helpful as it had inserted halfticks into the Y axis to try and improve the overall readability of the graph.

At some point in your travels, you unfortunately brought yourself undone by setting precision => 0, which caused those halfticks to round down, 4.5 to 4, 3.5 to 3 etc...

What you should be using is 'integer_ticks_only' => 1,.

I don't know what $popname was sposed to do, so I removed it. And it makes far more sense to declare the graph options in a single list rather than some up top in a separate hash, and others hidden lower down...

#!/usr/bin/perl
use strict;
use warnings;

use Chart::Mountain;
my $filename = $ARGV[0];

my $g = Chart::Mountain->new(1000,500);

$g->add_datafile( "$filename", 'set' );

$g->set (   'title'                 => 'Video Server Play Daily Hourly
+ Report',
            'grid_lines'            => 'true',
            'y_label'               => 'Numero Streams',
            'x_label'               => 'Dates',
            'include_zero'          => 1,
            'x_ticks'               => 'vertical',
            'tick_label_font'       => (GD::Font->Giant),
            'title_font'            => (GD::Font->Giant),
            'colors'                => {'dataset0' => [0,255,0]},
            'integer_ticks_only'    => 1,
            'misc'                  => [0,0,0],
);
            
$g->jpeg ("graph.jpg");
[download]

Data.txt:

29/04/2010-00.00 29/04/2010-00.30 29/04/2010-01.00 29/04/2010-01.30 29
+/04/2010-02.00 29/04/2010-02.30 29/04/2010-03.00 29/04/2010-03.30 29/
+04/2010-04.00 29/04/2010-04.30 29/04/2010-05.00 29/04/2010-05.30 29/0
+4/2010-06.00 29/04/2010-06.30 29/04/2010-07.00 29/04/2010-07.30 29/04
+/2010-08.00 29/04/2010-08.30 29/04/2010-09.00 29/04/2010-09.30 29/04/
+2010-10.00 29/04/2010-10.30 29/04/2010-11.00 29/04/2010-11.30 29/04/2
+010-12.00 29/04/2010-12.30 29/04/2010-13.00 29/04/2010-13.30 29/04/20
+10-14.00 29/04/2010-14.30 29/04/2010-15.00 29/04/2010-15.30 29/04/201
+0-16.00 29/04/2010-16.30 29/04/2010-17.00 29/04/2010-17.30 29/04/2010
+-18.00 29/04/2010-18.30 29/04/2010-19.00 29/04/2010-19.30 29/04/2010-
+20.00 29/04/2010-20.30 29/04/2010-21.00 29/04/2010-21.30 29/04/2010-2
+2.00 29/04/2010-22.30 29/04/2010-23.00 29/04/2010-23.30 
2 3 1 1 2 2 1 2 2 3 2 1 1 1 1 4 3 3 2 1 2 3 1 1 2 2 1 2 2 3 2 1 1 1 1 
+4 3 3 2 1 2 3 1 1 2 2 1 2
[download]