Maybe nothing. Hopefully your amended return will hit the IRS processing queue after your original return has been processed, in which case you'll have no problem. Since amended returns take longer to process than eFiled return, this will most likely be the case.
If they're both processed within a certain time frame, the IRS may contact you.
Either way, don't worry about it unless the IRS contacts you. It may cause you a bit of a headache to get things sorted out if they contact you, but nothing bad will happen.