Good point. This fixes it:

@files = grep { -f } glob '* .*';
@hash{ (map { (-s $_) . ".$_"} @files) } = @files;
@files =  @hash{ sort { $a <=> $b } keys %hash };
print map {$_,$/} @files;
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but it's rather a moot point - the Schwartzian Transform goes a step further and eliminates the hash.