use Data::Dumper;
$h{"a", 1, "b", 2} = 1;
$h{a1b2} = 2;
print Dumper \%h;

##</code><code>##

$VAR1 = {
          'a1b2' => 2,
          'a1b2' => 1
        };

##</code><code>##

use Data::Dumper;
$h{"a", 1, "b", 2} = 1;
$h{a1b2} = 2;
$_ = Dumper \%h;
s/(\P{IsPrint})/"\\x{".sprintf "%04x}", ord $1/ge;
print

##</code><code>##

$VAR1 = {
          'a1b2' => 2,
          'a\x{001c}1\x{001c}b\x{001c}2' => 1
        };