Receiving your ballot in the mail does not commit you to voting by mail.
Once you have filled in your ballot, sealed it, and mailed it you cannot vote again at your polling place or an early voting center. The key step there is mailing it.
If you decide not to mail your ballot, even though you voted and sealed it, you can tear it up and dispose of it.
When you go to your polling place, either on Election Day or during Early Voting, and attempt to check in, the election judge will see that you were mailed your ballot. At that time you can inform the election judge that you want to vote at the polling place instead. They will look you up, provide you with the correct ballot, have you vote, return the ballot to them and it will be placed in a large, secure Provisional Vote envelope.
This is a safeguard for anyone voting twice (by accident or otherwise).
How do we keep votes from counting twice? When you vote at the polling place, it immediately goes into the system. When your vote by mail ballot arrives at our office and we process that mail-in ballot, our system will indicate you voted on Election Day. The ballot submitted at the polling place is the vote that is counted. The other ballot is placed in a special, secure file in case we need to reference it, but is not counted.
The first vote received and entered in the system by the voter, is the one that is processed.