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

my (%file1,%file2);

## Open the 1st file
open(A,"file1");
while(<A>){
    chomp; 
    ## Split the current line on tabs into the @F array.
    my @F=split(/\t/); 
    push @{$file1{$F[0]}},@F[1..$#F];
} 

## Open the 2nd file
open(B,"file2");
while(<B>){
    chomp; 
    ## Split the current line on tabs into the @F array.
    my @F=split(/\t/); 

    if (defined($file1{$F[0]})) {
        foreach my $col (@{$file1{$F[0]}}) {
            print "$F[0]\t$col\t@F[1..$#F]\n";
        }
    }
}