#!/usr/bin/perl
use warnings;
use strict;

open my $IN1, '<', 'infile_1' or die $!;
open my $IN2, '<', 'infile_2' or die $!;
open my $OUT, '>', 'test2'    or die $!;

while (my $in1 = <$IN1>) {
    chomp $in1;
    defined(my $in2 = <$IN2>) or die "file2 too short\n";
    $in2 =~ s/\s//g;
    print {$OUT} join("\t", split /\s+/, $in1), "\t", join("\t", split //, $in2), "\n";
}
die "file1 too short\n" if <$IN2>;
close $OUT;