use warnings;
use strict;

my %data;

while (<DATA>) {
    chomp;
    my ($n, $d) = split;
    push @{ $data{$n} }, $d;
    }

print "$_    #    ", @{$data{$_}}, "\n" for sort keys %data;

__DATA__
0.000 -
0.331 W
0.370 D
0.000 M
0.331 K
0.370 N
0.000 M
0.331 T
0.370 E

##</code><code>##

>perl pm752936_1.pl
0.000    #    -MM
0.331    #    WKT
0.370    #    DNE