$_POST values with a dynamic list

[eluser]tomcode[/eluser]
The following two input fields produce an invalid form when repeated in a loop, they then do not dispose of unique names / ids :

Code:

<input name="image_name" type="hidden" value="<?PHP echo $r['imagename']; ?>" /><input type="submit" name="update_photo_desc" id="update_photo_desc" value="Update Description" />