The easy answer is, YES! You absolutely can!
If you already have access to the NAR + Photofy business subscription, you can go to http://photofy.com/remax-invite to register for the RE/MAX + Photofy business subscription.
To keep everything under ONE log in account, enter the same email address that you currently sign in with, your MCID, and complete any billing information necessary. Complete the registration process through to the "Success" message!
Open Photofy and Sign in with your email address and password. Now you should be able to toggle between the various accounts using the link at the bottom center of your main dashboard screen.