jQuery uncheck checkbox if disabled

<tr>
        <td>
        <input type="checkbox" value="14292" name="chec_emp[]" class="chec_emp">
        </td>
        <td>Test User One</td>
        <td>Autobot</td>
        <td>Shadow</td>
        <td>50</td>
    </tr>

 <tr>
        <td>
        <input type="checkbox" value="14293" name="chec_emp[]" class="chec_emp">
        </td>
        <td>Test User One</td>
        <td>Autobot</td>
        <td>Billed</td>
        <td>50</td>
    </tr>


    <tr>
        <td>
        <input type="checkbox" value="14292" name="chec_emp[]" class="chec_emp">
        </td>
        <td>Test User Two</td>
        <td>Autobot</td>
        <td>Billed</td>
        <td>50</td>
    </tr>

To disable checkbox with duplicate value, following code is used

$('.chec_emp').each(function(){
    if ($(this).is(':enabled')) {
        $('.chec_emp[value="'+$(this).val()+'"]').not(this).prop('disabled', 'disabled');
    }
});

But the below PHP condition makes it checked, as it falls under the defined condition

$class= "checked='checked'" ;
<input type="checkbox" class="chec_emp" <?php echo $class ;?> name="chec_emp[]" value="<?php echo $res_row['USERID']?>" />

The disabled checkbox is still checked. How to uncheck the disabled checkbox ?