How to submit multiple array checkbox with html forms

I am trying to submit multiple arrays with a checkbox form but I am only able to submit one array at the moment, here is what I have so far

In this example I am submitting an array of numbers with the delete[] array, this array gets processed properly, I also want to submit the array condition[] this does not get processed properly, what is the best way to solve this issue?

php code

$catalog = $database->getInventory();

if($catalog){   
   $numRows = sizeof($catalog);//count
   echo "<b>Book Count:</b> ".$numRows."<br>";

   echo "<form method='post' action='inventory.php'>";
   echo "<table id='example' class='tablesorter' border='0' cellpadding='0' cellspacing='1'>";
   echo "
      <thead>
         <tr>
           <th>ISBN</th>        
           <th>Title&nbsp;&nbsp;&nbsp;</th>
           <th>Rank&nbsp;&nbsp;</th>
           <th>Condition&nbsp;&nbsp;</th>   
           <th><input type='checkbox' name='delete' value='all' /></th>
         </tr>
      </thead>\n";


   foreach($catalog as $elem){
      echo "
         <tr>
            <td>".$elem["isbn"]."</td>
            <td>".$elem["title"]."</td>
            <td>".$elem["rank"]."</td>
            <td>".$elem["condition"]."</td>
            <td> 
               <input type='checkbox' name='add[]' 
                  value='".$elem['isbn']."_".$elem['condition']."_"."' />
            </td>
         </tr>";    
   }

   echo "</table>";
   echo "</form>";
}

example html markup

<form method='post' action='inventory.php'>
   <table>
      <tr>
         <td>
            <input type='hidden' name='addInventoryBook' value='1'>
            <input type='submit' value='Add' />
         </td>
      </tr>

      <tr>
         <td>
            <input type='checkbox' name='add[]' value='100001_used' />
         </td>
      </tr>

      <tr>
         <td>
            <input type='checkbox' name='add[]' value='100001_new' />
         </td>
      </tr>

      <tr>
         <td>
            <input type='checkbox' name='add[]' value='100003_new' />
         </td>
      </tr>

   </table>
</form>

php function

function Inventory(){   
   if(isset($_POST['addInventoryBook'])){
      if(isset($_POST['add']) && is_array($_POST['add'])){
     $arr = array();
         foreach($_POST['add'] as $checkbox){
            $temp = explode("_", $checkbox);

            $arr[] = array(
               "isbn"       => $temp[0],
               "condition"      => $temp[1],
               "sub_condition"  => $temp[2]
            );
         }              
     $this->addInventoryBook($arr); 
      }

      else{
         echo "No values have been set";
      }
 }


function addInventoryBook($arr){
   foreach($arr as $elem){
      //if used get sub-category
      if($elem['condition']=='used'){
         echo $elem['isbn']."-".ucfirst($elem['condition'])
            .ucfirst($elem['sub_condition'])."<br>";
      }

      else if($elem['condition']=='new'){
         echo $elem['isbn']."-".ucfirst($elem['condition'])."<br>";
      }

   }
}

All I want is to basically be able to pass two arrays to my php script

current output

100001
100002
100003

desired output

100001   good
100002   new
100003   new