Preserves order of both targetL and origin. 

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11106779
use warnings;
use List::Util qw( uniq );

my @AoH = (
  { count => 1, origin => "AMG", targetL => "foisonnement" },
  { count => 1, origin => "IDBR", targetL => "foisonnement" },
  { count => 1, origin => "IWWF", targetL => "gonfler" },
  { count => 1, origin => "IWWF", targetL => "due" },
  { count => 1, origin => "IWWF", targetL => "due" },
);

my %seen;
my @AoHfinal = grep
  {
  if( my $prev = $seen{$_->{targetL}} )
    {
    $prev->{count} += $_->{count};
    $prev->{origin} = join ' ', uniq split(' ', $prev->{origin}), $_->
+{origin};
    0 # skip duplicate
    }
  else
    {
    $seen{$_->{targetL}} = $_;
    }
  } @AoH;

use Data::Dump 'dd'; dd @AoHfinal;

[download]

Outputs: 

(
  { count => 2, origin => "AMG IDBR", targetL => "foisonnement" },
  { count => 1, origin => "IWWF", targetL => "gonfler" },
  { count => 2, origin => "IWWF", targetL => "due" },
)

[download]

In reply to Re: Counting elements in array of cases by tybalt89
in thread Counting elements in array of cases by Anonymous Monk

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