I would make a hash, keyed on the id's, with the open filehandles as values:

#!/usr/bin/perl

use strict;
use warnings;

open my $fh_a => "> a.txt" or die "open a.txt: $!";
open my $fh_b => "> b.txt" or die "open b.txt: $!";
open my $fh_c => "> c.txt" or die "open c.txt: $!";

my @a = qw /60622 60516 60201/;
my @b = qw /90210 60622 12345/;
my @c = qw /11412 32134 60201/;

my %data;
   @data {@a} = ($fh_a) x @a;
   @data {@b} = ($fh_b) x @b;
   @data {@c} = ($fh_c) x @c;


while (<DATA>) {
    chomp;
    my ($fn, $ln, $id) = split /,/;
    next unless $data {$id};
    print {$data {$id}} "$_\n";
}

close $fh_a or die "close a.txt: $!";
close $fh_b or die "close b.txt: $!";
close $fh_c or die "close c.txt: $!";

__DATA__
Homer,Simpson,60622
Clark,Kent,90210
Fred,Flintstone,00987
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Abigail