Yes, you still collected unemployment.  The correct procedure would be to cash the checks and then pay them back when unemployment marked them as an overpayment,  

Their computer system will not know how to handle getting back voided checks and you may be a long time trying to get things straightened out.  At some point, you may have to engage a lawyer to try to straighten out the confusion that this is going to cause.

In the past, when these things were done by humans, you method would have worked.

Thank you. Is it still possible to cash them? They are over a year old.

Probably not.  Most checks must be cashed within six months.  I would call the state unemployment office and get someone to work with you to resolve this.

I would call the state unemployment office

That's probably the best move. But since history shows that communication is seriously lacking in many government agencies, the very first question you should ask is, "To whom am I speaking please?". Then make sure you document everything, to include the date/time of your phone call. 

When you end up having to call back multiple times in what may (or may not) be a fruitless effort to fix things, chances are slim to none that you will ever speak to the same person twice.