jQuery Disable checkbox with same value

So this has to be the easiest question of the day. I have below HTML structure where all input checkbox values must be unique.

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

The value 14292 is generated twice here.

1. How can I disable checkbox with duplicate value


2. How can I disable checkbox with <td>Shadow</td>