how to stop repeatitive image display in below program

i want to get rid of repeated images as i am getting repeated result in ajax success and for explaination i have tags images on particular friends name so i want to all those images if that particular names have been selected from checkbox but if i get common images between two than i am not able to display as common below is form1.php

function check(){


var ln=checkbox.length-$('input[name="checkbox[]"]:checked').length;
//alert(ln);
$("#im").empty();
var boc="";
var b="";
var test=[];
var foo=[];
var m=0;
$('input[name="checkbox[]"]:checked').each(function() {

  boc = this.value;

              $.ajax({
                  type:"POST",
                  url:"prac.php",
                  data:{boc:boc},
                 dataType: "json", 
                                  success: function(data) {
                                  b=data
                                  for(var i=0;i<b.length;i++)
                                  {


                                                                      var elem = document.createElement("img");

                                                                            elem.setAttribute("src", b[i]);
                                                                            elem.setAttribute("height", "200");
                                                                            elem.setAttribute("width", "200");
                                                                            elem.setAttribute("alt", "");
                                                                            document.getElementById("im").appendChild(elem);
                                                                            $("#im img").css('padding','10px');

                                  }




                                    },  


                    });


                                                      });


}

</script>


<?php            
$servername="localhost";
$username="root";
$password="";
$dbname="baba";

$conn=mysqli_connect($servername,$username,$password,$dbname);

$sql="select * from babas  ";
$result=mysqli_query($conn,$sql);
while($row=mysqli_fetch_row($result))
{
?>

<input type="checkbox"  name="checkbox[]" id="checkbox" value="<?php echo $row[1];  ?>" onclick="check()"   ><i></i><?php echo $row[1];?>
<br/>

<?php
}
?>  


<div id="im">
</div>

**This is prac.php**


include "database.php";

$name = $_POST['boc'];

$query="SELECT * FROM `photo_tag` inner join photos on photo_tag.photo_id=photos.photo_id where baba_name='$name'";

$result=mysqli_query($conn,$query);


while($row=mysqli_fetch_row($result))

{

  $pht[]= 'photo/'.$row[5];


}


echo json_encode($pht);