Hello and Welcome to the Community!
It's certainly possible, to do this simply select your desired subscription from our webpage here > add a payroll plan on the pop-up if applicable and select continue > on the screen which appears, see 'Already have an account?' and click 'Sign-in' and continue to buy.
Once you have setup the account, you will see both listed when signing in and can flick between the two by selecting the main settings wheel > switch company. :)