#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11148698
use warnings;
use List::AllUtils qw( uniq_by );

open my $fh, '<', \<<END;
id  name
123 john
34  john
567 john
11  peter
899 peter
87  helen
END

<$fh>; # skip first line
print uniq_by { (split)[1] } <$fh>;