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<?php $ar = [ ["uid" => 1, "title" => "Title A", "tstamp" => "1580296755",], ["uid" => 2, "title" => "Title B", "tstamp" => "1580296755",], ["uid" => 3, "title" => "Title B", "tstamp" => "1580296755",], ["uid" => 4, "title" => "Title C", "tstamp" => "1580296755",], ]; $tmp = []; foreach($ar as $ind=>$set){ if(!in_array($set['title'],$tmp)){ $tmp[] = $set['title']; } else { unset($ar[$ind]); } } print_r($ar);
Output for 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.13
Array ( [0] => Array ( [uid] => 1 [title] => Title A [tstamp] => 1580296755 ) [1] => Array ( [uid] => 2 [title] => Title B [tstamp] => 1580296755 ) [3] => Array ( [uid] => 4 [title] => Title C [tstamp] => 1580296755 ) )

preferences:
126.87 ms | 408 KiB | 5 Q