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

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