Try this.

use warnings;
use strict;

my %data = ();

my $str1 = 'flinstones,fred,barney,willma,betty';
my $str2   = 'flinstones1,fred1,barney1,willma1,betty1';

my @tmp1  = split(/,/, $str1);
my @tmp2 = split(/,/, $str2);

my $key1  = shift @tmp1;
my $key2 = shift @tmp2;

push(@{$data{$key1}} , @tmp1);

push(@{$data{$key2}} , @tmp2);

foreach my $key (keys %data){
  foreach (@{$data{$key}} ) {
      print "$key - $_ \n";
  }
}
[download]

Output:
-------
flinstones1 - fred1
flinstones1 - barney1
flinstones1 - willma1
flinstones1 - betty1
flinstones - fred
flinstones - barney
flinstones - willma
flinstones - betty
--
Sivakumar