delete duplicate hash value's

[juo]

Anybody has an idea to easy delete a hash key the moment it has duplicate & values in another key. In the example below you can see that Pieter Test and Sally cummings have the same value's. When all the values are the same in one of the keys then one of them can be removed either Sally cummings or Pieter Test.

%students = ();
$students{"Nick Plato"}=(
        {
                "year"=>"2",
                "GPA"=>"2.5",
                "major"=>"Phys. Ed.",
                "email"=>"nplato\@school.edu"
        }
);


$students{"Mary Pitts"}=(
        {
                "year"=>"4",
                "GPA"=>"4",
                "major"=>"Economics",
                "major"=>"Economics",
                "email"=>"mpitts\@school.edu"
        }
);

$students{"Sally Cummings"}=(
        {
                "year"=>"1",
                "GPA"=>"3.3",
                "major"=>"Undecided",
                "major"=>"Undecided",
                "email"=>"scummings\@school.edu"
        }
$students{"Pieter Test"}=(
        {
                "year"=>"1",
                "GPA"=>"3.3",
                "major"=>"Undecided",
                "major"=>"Undecided",
                "email"=>"scummings\@school.edu"
        }
);