Roth IRA Backdoor Conversion

Hi, I did Roth IRA backdoor conversion last year (2020), for both the year 2019 and 2020. Therefore, I have $12000 on my 1099R. I followed the method from the link below to report it on TurboTax:

https://thefinancebuff.com/how-to-report-backdoor-roth-in-turbotax.html

 

I was only able to add the 2020 IRA contribution and there is no where to put in the 2019 one. What should I do to claim the 2019 contribution? Do I need to go back and file the 2019 tax amendment?