#!/usr/bin/perl

use warnings;
use strict;

use FindBin qw($Bin);
use File::Spec::Functions qw( catfile );

use Win32::OLE qw(in);
use Win32::OLE::Const 'Microsoft Excel';
$Win32::OLE::Warn = 3;

my $excel = get_excel();
$excel->{Visible} = 1; # for illustration only

my @src = map $excel->Workbooks->Open($_),
      map catfile($Bin, $_),
      qw(one.xls two.xls)
      ;

my $target = $excel->Workbooks->Add(xlWBATWorksheet);
my $before = $target->Worksheets->Item(1);

for my $book ( @src ) {
my $sheets = $book->Worksheets;
my $it = Win32::OLE::Enum->new($sheets);

while (defined(my $sheet = $it->Next)) {
    $sheet->Copy($before);
    }
}

$before->Delete;

$_->Close for @src;
$target->SaveAs(catfile($Bin, 'test.xls'));
$target->Close;

sub get_excel {
my $excel = Win32::OLE->GetActiveObject('Excel.Application');
unless(defined $excel) {
    $excel = Win32::OLE->new('Excel.Application', sub { $_[0]->Quit })
        or die "Oops, cannot start Excel: ",
               Win32::OLE->LastError, "n";
}
return $excel;
}