For Online you could use 1 account but it only saves the last one. What info would you import?
The Desktop program is only sold as a download. It can do unlimited returns so you can do test returns. You can save a return with another name to test in. It also has a What-If worksheet and you can enter directly into the forms. And many other features and advantages over the Online version.
You can buy the Desktop CD/Download program here,
https://turbotax.intuit.com/personal-taxes/cd-download/
2024 Desktop System Requirements
TurboTax® Desktop 2023-2024 System Requirements
