I think I found a solution to this! To make multiple profiles with the same email address, add a "+" sign and a word (could be anything, the user's first name, for example) after the regular email address and before the "@" symbol. So if the user's email is:
[email protected] and you want to create another profile using the same email address, use the email address
[email protected] to make another profile on Planning. I just tested this and it works. It created another profile, but sent the confirmation email to my regular email address that I already have on my profile. I could still sign into both accounts. Now just set different names for both profiles so they know who the invite is for.