To amend twice you must delete the form 1040-X but leave the revisions you made on 1040.
You only get one 1040-X e-File and that only if you did e-File 1040.
If you are going to amend a second time, you have to file a paper Form 1040-X.
Note : many users, including me , have reported that amending twice doesn't work.
I haven't tried it with TurboTax 2020 to see if there are improvements this year.
Maybe you could report back how it goes for you.
