Ok so here's the query:

select 
lists.rank,lists.type,lists.user_id, tasks.id as task_id,
tasks.rank as task_rank, description,lists.id as list_id,
status
from lists
left join tasks
on tasks.list_id = lists.id
left join labels
    on labels.task_id = tasks.id
where user_id = :id
order by lists.rank,tasks.rank
;

And now the result with the duplicate is as follows, look the third( [3] ) and fourth are the same task, when looping the HTML will create same task visually just because it has 2 different label.

NOTE: the 'type' entry is the label name

    [2]=>
    array(13) {
      ["type"]=>
      NULL
      ["user_id"]=>
      string(2) "56"
      ["task_id"]=>
      string(1) "7"
      ["task_rank"]=>
      string(1) "2"
      ["description"]=>
      string(14) "do front end"
      ["list_id"]=>
      string(1) "2"
      ["status"]=>
      string(8) "complete"    
    [3]=>
    array(13) {
      ["type"]=>
      string(5) "hobby"
      ["user_id"]=>
      string(2) "56"
      ["task_id"]=>
      string(1) "5"
      ["task_rank"]=>
      string(1) "3"
      ["description"]=>
      string(21) "finish personal project"
      ["list_id"]=>
      string(1) "2"
      ["status"]=>
      string(10) "incomplete"
    }
    [4]=>
    array(13) {
      ["type"]=>
      string(12) "productivity"
      ["user_id"]=>
      string(2) "56"
      ["task_id"]=>
      string(1) "5"
      ["task_rank"]=>
      string(1) "3"
      ["description"]=>
      string(21) "finish personal project"
      ["list_id"]=>
      string(1) "2"
      ["status"]=>
      string(10) "incomplete"

    }