use strict;
use Tie::DxHash;

my %foo;
tie %foo, 'Tie::DxHash';

%foo = qw (    one 1.2
               one 1.6
               one 1.9
               two 2
               three 3 );
my @keys = keys %foo;
print "@keys\n";

# if @keys only has each key once, try this:
foreach my $key (@keys)
{
    print "$key, " foreach ($foo{$key})
}


##</code><code>##

%hash = ( one => [1.2, 1.6, 1.9],
          two => [2],
          three => [3]);