Can I add a PNG file to an existing PowerPoinit presentation using MATLAB?

I'm attempting to add a PNG file to slide 2 of an an existing 2-slide PowerPoint presentation using the following code;

% Clear out all workspace variables, close all open figures, and clear the
% command window
clear all;
close all;
clc;

% Create Common Object Model (COM) server so MATLAB can export data to
% PowerPoint
g = actxserver('powerpoint.application');

% Open PowerPoint and make it visible
g.Visible = 1;
Presentation = g.Presentation;

% Prompt the user for the PowerPoint file to open
[fn, pn] = uigetfile('*.ppt', 'Select PowerPoint File To Amend');
filename = fullfile(pn, fn);
Presentation = invoke(Presentation, 'open', filename);

% Get current number of slides
slide_count = get(Presentation.Slides, 'Count');

% Add Dice PNG to slide 2 in the existing Test slides file
slide_count = int32(double(slide_count));
PNG_To_Slide = invoke(Presentation.Slides, 'Add', slide_count, 1);
Image1 = PNG_To_Slide.Shapes.AddPicture('C:\Documents and Settings\My Documents\MATLAB\PNG_Dice.png', 'msoFalse', 'msoTrue', 0,75,620,440);

% Save PowerPoint presentation
Presentation.SaveAs('C:\Documents and Settings\My Documents\MATLAB\New_Slides.ppt');

% Close PowerPoint as a COM automation server
g.Quit;
g.delete;

While this does place the PNG file in the existing PowerPoint slides, I've had to add another slide just to do it. The result is a 3-slide PowerPoint file with the dice PNG on slide 2 of 3 - instead of slide 2 of 2.

Is it possible to add a PNG to an existing PowerPoint presentation without having to add a separate slide?