This is incorrect. The program merely gives you a chance to claim your stimulus if you have not already gotten it. Yes, if you say you have not gotten it when your really did, it will add it to your refund. If you then realize you made a mistake and did get it and remove the amount, it will look like your refund went down.
It would be the same situation if you entered your withholding twice and get an exaggerated refund, realized your error, and corrected the amount.
