The short answer is: use a hash, keyed by the values that you want to test for equality. Something like:

for (@fuente) {
  my @parts = split /\|/;
  ++$seen{$parts[1]} = $_;
}
for (@fuente2) {
  my @parts = split /\|/;
  if ($seen{$parts[2]}) {
     print $seen{$parts[1]}; # That's the matching line from @fuente
     print; # That prints the line from @fuente2
  }
}
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