Do not think of your problem as removing numeric data. Look at the problem as one of combining all the alpha data that belongs to the same numeric 'key'. In this view, store the data as a hash-of-arrays with the numbers as the keys.

use strict;
use warnings;
use Autodie;
open my $FH, '<', 'jzelkowsz.dat';
my %data;
while (my $pair = do{ $/ = ', ';<$FH>}) {
    my ($numeric, $alpha) = split qr/,/, $pair;
    push @{$data{$numeric}}, $alpha;
}
foreach  my $num (sort keys %data) {
    $" = ',';
    $\ = "\n";
    print "$num|@{$data{$num}}";
}
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