If a png file can not be appended, atleast it can be written. How do I write images from 2 different png files to a single png file?

I tried

#!/usr/local/bin/perl   
use Image::Magick;
my($image, $p, $q);  
$image = new Image::Magick;  
$image->Read('d:\\d\\Graph.xls..PNG','d:\\d\\Sample.jpg');    
$image->Write('d:\\pimage.jpg');
[download]

but this writes the images to two files 'pimage.jpg.0' & 'pimage.jpg.1'(each having one image). I want both the images to be in a single png file. How do I get it?

Thanks & Regards

Nalina