Is this possible using GD:Graph?

No. There is no facility in the module for that.

If not, is there a workaround to get this done?

A work-around would be to give datasets A & B different X values to datasets C & D and use custom labels to tie them together.

Ie. If (say) for April the values were: a(4,10), b(4,12), c(4,3), d(4,7) then adjust them so that they become a(3.75,10),b(3.75,12), c(4.25,3), d(4.25,7).

That way, with cumulate enabled you should get:

25|
  |
20|              B
  |              B
15|              B
  |              B
10|              A D
  |              A D
 5|              A D
  |              A C
 0+-------------------------------------------------
      1   2   3   4   5   6   7   8   9  10  11  12
[download]

Update: For hbar graphs it would be the Y values you adjust.

I Have tried with my below code as you have said, but its not working. Can you please help me and let me know where i am doing wrong.

use GD::Graph::bars; 
use GD::Graph::hbars; 
require '/root/.cpan/build/GDGraph-1.48/samples/save.pl';

my @data = ( 
["1st","2nd"], 
[ (3.75,10),(3.75,12) ], 
[ (4.25,3),(4.25,7) ], 
); 

my @names = qw/sample15 sample15-h/; 

for my $my_graph (GD::Graph::bars->new, GD::Graph::hbars->new) 
{ 
my $name = shift @names; 
print STDERR "Processing $name\n"; 

$my_graph->set( 
x_label => 'X Label', 
y_label => 'Y label', 
title => 'Stacked Bars (incremental)', 
#y_max_value => 50, 
#y_tick_number => 10, 
#y_label_skip => 2, 
cumulate => 4, 
overwrite => 1,
borderclrs => $my_graph->{dclrs}, 
#cycle_clrs => 4, 
bar_spacing => 2, 
#shadow_depth    => 4, 

transparent => 0, 
); 

$my_graph->set_legend( qw(offset increment more)); 
$my_graph->plot(\@data); 
save_chart($my_graph, $name); 
}
[download]

I Have tried with my below code as you have said, but its not working.

I ran your code and it produced this and this which looks pretty much exactly how I envisioned it would.

So, how is it "not working"?

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