I sent my payment via regular mail. 1 month later still don't have my registration renewal, so I start worrying. I call my bank to block the check, and go to DMV offices in person and make a payment using a credit card.
After a couple of weeks I receive 2 letters from DMV the same day. One saying I double paid, and hence they are now include a check with my payment back. And another one saying my original check has bounced and that now I will have to make the payment using cashier's check and pay an extra $20 for the bounced check.
I get a cashier check for the amount plus the $20 and make yet another payment.
A couple of weeks later I receive another letter from DMV with a check returning the $20 penalty.
So overall in the end we did balance things out, but took a while :D