perl -MData::Dumper -E 'my $r=[map { id=>$_ }, ("a".."c","b")]; 
     say Dumper $r;
     my %h;
     my @z= map {$h{$_->{id}}++ ?():$_ } @$r;
    say Dumper \@z'

##</code><code>##

$VAR1 = [
          {
            'id' => 'a'
          },
          {
            'id' => 'b'
          },
          {
            'id' => 'c'
          },
          {
            'id' => 'b'
          }
        ];

$VAR1 = [
          {
            'id' => 'a'
          },
          {
            'id' => 'b'
          },
          {
            'id' => 'c'
          }
        ];