G'day mao9856,

I'd read through one file and store all of its data in a hash; then read through the remaining files, removing hash data that wasn't common. Given these files (in the spoiler) using data from your OP:

This code:

#!/usr/bin/env perl

use strict;
use warnings;
use autodie;

my @files = glob 'pm_1206312_in*';
my %uniq;

{
    open my $fh, '<', shift @files;

    while (<$fh>) {
        my ($k, $v) = split;
        $uniq{$k} = $v;
    }
}

for my $file (@files) {
    my %data;
    open my $fh, '<', $file;

    while (<$fh>) {
        my ($k, $v) = split;
        $data{$k} = $v;
    }

    for (keys %uniq) {
        delete $uniq{$_} unless exists $data{$_} and $uniq{$_} eq $dat
+a{$_};
    }
} 

printf "%s %s\n", $_, $uniq{$_} for sort keys %uniq;
[download]

Produces this output:

ID121 ABC14
ID122 EFG87
ID157 TSR11
[download]

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