No, you can cash the check or at least hold on to it. The IRS will probably end up resolving this by adjusting your tax return to remove the stimulus payment that you claimed. The IRS originally said that they would only issue stimulus payments until January 15. But they are continuing to issue payments until February 5.
A lot of people filed for the stimulus payment and then received a stimulus check, debit card, or deposit. The IRS has not yet told us how they will handle this. But if you destroy the check and then they take the payment from your refund, you would have to file paperwork to have the check reissued.
