For now, do nothing. The IRS has the authority to treat errors with the stimulus payment as mathematical errors, which means they can correct them without needing to send letters or ask for an amended return. Of course, we won't know how they actually handle this situation until tax processing gets going. I suspect that it will delay your refund, though, if your return gets kicked out of the automated system and has to be reviewed by a person. Wait and see if they reduce your refund or send a letter or do something else.
