#!/usr/bin/perl

use strict;
use warnings;

open FILE, 'file.1.dat';
my $hist = {map{ chomp; $_ => 1 } @{[<FILE>]}};
close FILE;

open FILE, 'file.2.dat';
while ( my $line = <FILE> ) {
     chomp( $line );
     my ( $file, $account, @other ) = split( /\t/, $line );
     next if ( exists( $hist->{$account} ) );
     print "$account:\t$file\n";
}
close FILE;

exit;
__END__