Thanks for the very rapid replies. Ok, so using Data::Dumper in line 4 of script 2 gives

OUTPUT:

$VAR1 = {
          'c' => 1,
          'wrong' => {},
          'a' => 1,
          'b' => 1,
          'd' => 1
        };
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So.. print keys %{$hash{'wrong'}} causes an element to be added to %hash, the key is 'wrong' and the value is a reference to an empty, anonymous hash. Have I got that correct?