Big Mistake. You just doubled the opportunity for the 'Rats to correct their mistake; the mail carrier, postal workers and even "impartial" election employees then had the opportunity to "correct" their mistake.
I would have mailed a copy of the card back and another copy to my local newspaper, and delivered the original card to the local Republican headquarters.
Maybe I should check my hubby's briefcase to see if it's still there. He's not the most conscientious when it come to remembering to run errands.