For me to vote early in MN in person (a week before the election) I had to fill out an absentee form to get a ballot. I was able to track my ballot and it said that my ballot was received that same day. I would not worry about it too much as long as it says the received ballot was on the same day that they voted in person.
Depends on the area. The key thing is for your parents to call and ask their registrar of voters office to get the full details.
Seems suspicious
Best thing to do is call the local election officals and ask.
For me to vote early in MN in person (a week before the election) I had to fill out an absentee form to get a ballot. I was able to track my ballot and it said that my ballot was received that same day. I would not worry about it too much as long as it says the received ballot was on the same day that they voted in person.