Careful when using Data::Dumper to dump strings.

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

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

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

$VAR1 = {
          'a1b2' => 2,
          'a\x{001c}1\x{001c}b\x{001c}2' => 1
        };
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("\x{001c}" eq "\034" eq chr(28) eq $; See first reply.)