Fair enough comment and could point to the problem.

CAM::PDF was last updated a decade ago; PDF::API2 was last updated a few months ago. When the OP sorts out the API::PDF2 installation problem, something like this might be a better way to go:

#!/usr/bin/env perl

use strict;
use warnings;

use PDF::API2;

my $src = PDF::API2->open('DX.pdf');
my $pdf = PDF::API2::->new();

for my $page_num (2 .. $src->page_count() - 1) {
    $pdf->import_page($src, $page_num, $page_num - 1);
}

$pdf->save('DXout2.pdf');
[download]

I did a visual check of "DXout2.pdf": it looks the same as "DXout.pdf" but is substantially larger.

$ ls -al
...
-rw-r--r-- 1 ken None  3855 Mar 25 09:10 DX.pdf
-rw-r--r-- 1 ken None  3277 Mar 25 09:42 DXout.pdf
-rw-r--r-- 1 ken None  5525 Mar 25 10:46 DXout2.pdf
...
[download]

If the OP chooses that route, an improvement on my simplistic solution may be worth investigating.

Edit (fixed typo): s/API::PDF2/PDF::API2/