By Chandelis Duster, CNN

(CNN) -- Michigan and North Carolina election officials reminded citizens Thursday that voting twice is illegal and they could be prosecuted after President Donald Trump encouraged voters to do so.

The warnings come after Trump, while speaking to reporters Wednesday in Wilmington, North Carolina, encouraged voters to test the state's voting system when asked if he was confident in the state's mail-in voting system. Vote-by-mail has become a key issue in the lead up to the 2020 election as many states are resorting to an increase in voting by mail amid fears of spreading coronavirus at the polls.

Trump, who has also questioned mail-in voting and spread false information about the practice leading to wide-spread fraud, said for people to send in their ballots and then go vote as well.

"Send them in strong, whether it's solicited or unsolicited. The absentees are fine. You have to work to get them, you know," Trump said.

"And you send them in, but you go to vote. And if they haven't counted it, you can vote. So that's the way I feel," he said.

Americans are only allowed to vote once during an election.

Michigan Attorney General Dana Nessel on Thursday retweeted a news article about the President's remarks and wrote "don't try this at home."

"Hey folks. Attorney General Nessel here-top law enforcement official in Michigan, for those keeping track. Don't try this at home. I will prosecute you," she tweeted.

"Also, this might be a good time to remind people not to drink bleach," she added in reference to a moment earlier this year when Trump suggested sunlight and ingesting disinfectants could help cure coronavirus.

Karen Brinson Bell, executive director of the North Carolina State Board of Elections, also sent a message to North Carolina residents reminding them that voting twice is illegal and is a Class 1 felony in the state.

"Attempting to vote twice in an election or soliciting someone to do so also is a violation of North Carolina law," Brinson Bell said in a statement, adding that there are procedures in place that prevent double voting. "Electronic pollbooks with information about who has already voted are used at every early voting site. If a voter tries to check in who has already voted, they will be prevented from voting a regular ballot."

She added, "A voter will be offered a provisional ballot if they insist on voting, and this ballot will be researched after Election Day to determine whether it should be counted."

North Carolina Attorney General Josh Stein told CNN's John King Thursday that Trump gave "poor advice" when telling voters to vote twice.

"When you mail in your absentee ballot, you can track it online, and it will show on the website that your ballot has been received. There is zero reason to go vote in person once you've mailed in your ballot," he said.

Asked if he believed Trump is trying sew doubt and uncertainty or if he was just confused, Stein, a Democrat, said "he's trying to create this widespread belief that the election outcome is not going to be legitimate, and it's wrong."

Asked by CNN's Wolf Blitzer on Wednesday if Trump was encouraging people to commit a crime by voting twice, Attorney General William Barr said "I don't know exactly what he was saying, but it seems to me what he's saying is, he's trying to make the point that the ability to monitor this system is not good."

"And if it was so good, if you tried to vote a second time you would be caught if you voted in person," Barr continued.

When Blitzer stated that voting twice that way would be illegal, Barr said he didn't know the laws in each state. White House press secretary Kayleigh McEnany claimed Thursday on Fox News that Trump was "not suggesting anyone do anything unlawful."

"What he said very clearly there is make sure your vote is tabulated and if it is not, they didn't vote. Basically when you get a absentee ballot and you send it in, there are poll books and it is recorded that you have tried to vote, that you have in fact voted. And if you show up at a polling site they look at the poll book and say your vote's been counted," she said.

Brinson Bell discouraged North Carolinians from "showing up at the polls on Election Day to check whether their absentee ballot was counted," saying it will increase wait times and the changes of spreading coronavirus. She said that those who send in an absentee ballot can check online to make sure it has been accepted by the county board of elections.