Given that you have reasons to hold your people in a list then a quick way to search for particular first names is to index them as other replies have suggested. You can build the index as you build the @PEOPLE list and if you make the index a HoL with key being name and value being record no. in @PEOPLE you can extract all of your Johns using a slice.

#!/usr/local/bin/perl -w
#
use strict;

our @PEOPLE = ();
our $rhFirstNameIdx = {};
our $recCt = 0;

while(<DATA>)
{
    chomp;
    my ($fname, $lname) = split;
    push @PEOPLE, {fname => $fname, lname => $lname};
    push @{$rhFirstNameIdx->{$fname}}, $recCt ++;
}

our $wanted = 'John';
our @found = @PEOPLE[@{$rhFirstNameIdx->{$wanted}}];
print "First - $_->{fname}, Last - $_->{lname}\n" for @found;

__END__
Fred Bloggs
Charley Farley
John Doe
Peter Piper
Mary Poppins
John Smith
Bill Bailey
[download]

The little script above illustrates this and prints out the entries for John Doe and John Smith.

Cheers

JohnGG