#!perl
use strict;
use warnings;

sub both_byte_orders_32 {
    my $data = shift;
    $data = pack 'H*', sprintf '%08x', $data;
    return reverse($data).$data
}

print both_byte_orders_32(305419896);
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e.g. 305419896 in hex is (12345678) so formatted string should be (78 56 34 12 12 34 56 78)

The Question
although this works I have a nagging suspicion that this isn't The Best Way (tm) - is there some way to incorporate the reversing (little/big endian or something) into the pack/sprintf somehow - pack is still mysterious to me!