You cannot install two copies of the personal TurboTax software for the same year on one computer. Personal TurboTax software means TurboTax Basic, Deluxe, Premier, or Home & Business - anything except TurboTax Business (which is not the same as Home & Business). You can install one personal edition and TurboTax Business on the same computer. You can install personal editions for different years on one computer, so you could have 2017 Deluxe and 2018 Deluxe on the same computer. But you cannot install two copies of 2018 Deluxe on one computer, and you cannot install, for example, 2018 Deluxe and 2018 Premier on the same computer.
