Do you mean a return for someone else? You cannot file a second tax return for yourself. If you filed a tax return and left out some of your income etc. you have to wait for the first return to be fully processed and then prepare an amended return.
If you mean you need to prepare a return for some other person:
If you filed your 2020 tax return already but need to make changes then it depends if your return got rejected or accepted.
Please see the links below when Form 1040X is available:
What i mean is i had couple of jobs, so i need file every one by it self, so my question is how? Do i need creat couple accounts or i can do it on one account? Do i need to wait to receive the one that I filled already ,or i can submit all of them in one day!