clone.conf

input {
  stdin {
    codec => json {}
  }
}

filter {
  clone {
    clones => ['cloned_test_event']
  }
  if ([type] == 'cloned_test_event') {
    mutate {
      remove_field => ["title"]
    }
  }
}

output {
  stdout { codec => rubydebug { metadata => true } }
}

$ echo '{"name": "a test","title": "some title"}' | bin/logstash -f clone.conf
Settings: Default pipeline workers: 4
Pipeline main started
{
          "name" => "a test",
         "title" => "some title",
      "@version" => "1",
    "@timestamp" => "2016-11-07T19:30:37.062Z",
          "host" => "peanut.local"
}
{
          "name" => "a test",
      "@version" => "1",
    "@timestamp" => "2016-11-07T19:30:37.062Z",
          "host" => "peanut.local",
          "type" => "cloned_test_event"
}
Pipeline main has been shutdown
stopping pipeline {:id=>"main"}

$ cat clone.conf && echo '{"name": "a test","title": "some title"}' | bin/logstash -f clone.conf
input {
  stdin {
    codec => json {}
  }
}

filter {
  clone {
    clones => ['cloned_test_event', 'second_clone']
  }
  if ([type] == 'cloned_test_event') {
    mutate {
      remove_field => ["title"]
    }
  }
}

output {
  stdout { codec => rubydebug { metadata => true } }
}
Settings: Default pipeline workers: 4
Pipeline main started
{
          "name" => "a test",
         "title" => "some title",
      "@version" => "1",
    "@timestamp" => "2016-11-07T19:39:34.101Z",
          "host" => "peanut.local"
}
{
          "name" => "a test",
      "@version" => "1",
    "@timestamp" => "2016-11-07T19:39:34.101Z",
          "host" => "peanut.local",
          "type" => "cloned_test_event"
}
{
          "name" => "a test",
         "title" => "some title",
      "@version" => "1",
    "@timestamp" => "2016-11-07T19:39:34.101Z",
          "host" => "peanut.local",
          "type" => "second_clone"
}
Pipeline main has been shutdown
stopping pipeline {:id=>"main"}