especially Tie::Hash::Layered seems identical in most features (maybe not in the order)

Thanks!

Just this

  # tie the new hash with the initialised hashes above
  tie %hash, 'Tie::Hash::Layered', (\%test1, \%test2);
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could be simplified to

  tie %hash, 'Tie::Hash::Layered', \( %test1, %test2 );
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