Do you mean a tax return for someone else? Or you have another W2 or 1099 to enter for yourself? You can only submit and file 1 tax return. It should have all your income on it. If you filed without the other form you need to file an amended return to add it.
Has your return been Accepted?
You should not amend until the first return has fully processed and you get the first refund or your tax due payment has cleared.
How to Amend this year
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-curr...
