Okay, if you are thinking about not cashing them anyway, I would try sending them back to the people with a nice letter explaining what happended and ask them to replace them with a currently dated check. Because this was your oversite , I would enclose a self addressed, stamped envelope so they would have no excuse for not sending you a new check except for the fact they are deadbeats. Hope you get your money, because they know they owe it. Good luck.