use strict;
use warnings;
use Data::Dumper;
my @students = (
    {
	name  => "Gil",
	college => "Yale",
    },
    {
	name  => "Gil",
	college => "Harvard",
    },
    {
	name  => "Gil",
	college => "Harvard",
    },
    );
my @unique = do { 
    my( %seenName, %seenCollege ); 
    grep { !$seenName{$_->{name}}++ or !$seenCollege{$_->{college}}++ } @students};
print Dumper \@unique;