#! perl
use strict;
use warnings;
use Data::Dump;

my %dedicated;

while (my $line = <DATA>)
{
    chomp $line;

    my ($key, $values) = split ' ', $line;

    push @{ $dedicated{$key} }, $_ for split ',', $values;
}

dd \%dedicated;

__DATA__
names1 john,bob,stu
names2 mike,john,bob
names3 blah