Some tips that will save you frustration – read the directions when voting by mail wherever you vote. It’s that lesson taught again and again in school worth learning.
If you got a mail-in ballot and then decided to vote in person you can. It’s best to bring your ballot back and surrender it. Those who don’t must vote provisionally and the vote won’t be counted till after the deadline for mail-in ballots. It must be determined that that mail in wasn’t used.
Make sure you know where to deposit your ballot. In Chicagoland, if you’re in the city, use a City of Chicago drop boxes. If you’re in the suburbs, use the suburban drop boxes. Thus your ballot is sure to be counted. If you insist on arguing with the election judge to drop a ballot in the wrong drop box, no one can insure that your ballot will get to the right place in time.