Greetings all,
This works for a small array. Im not sure how well it will scale for 4000 elements, hopefully you have enough memory for it.

#!/usr/bin/perl -w
use strict;
my @array = (
    { a => 1, b => 2, c => 3},
    { a => 1, b => 2, c => 3},
    { a => 1, b => 2, c => 3},
    { a => 2, b => 2, c => 3},
    { a => 2, b => 1, c => 3}
);
my @unique = do{
    my %seen = map{join(":", values %{$_}), $_} @array;
    values %seen;
};
foreach(@array){
    foreach my $key(sort keys %{$_}){
        print "$key => $_->{$key}:";
    }
    print "\n";
} 
print "\nunique\n";
foreach(@unique){
    foreach my $key(sort keys %{$_}){
        print "$key => $_->{$key}:";
    }
    print "\n";
}
[download]

output

a => 1:b => 2:c => 3:
a => 1:b => 2:c => 3:
a => 1:b => 2:c => 3:
a => 2:b => 2:c => 3:
a => 2:b => 1:c => 3:

unique
a => 2:b => 2:c => 3:
a => 1:b => 2:c => 3:
a => 2:b => 1:c => 3:
[download]

This code assumes that the hashes have the same keys just different values. If this is not the case change the line

my %seen = map{join(":", values %{$_}), $_} @array;
[download]

to

my %seen = map{join(":", keys %{$_}), $_} @array;
[download]

-InjunJoel