Compare “what” is my question. Email address? Totally seperate. Employers? All mine on FB are fictitious. Date of birth and hometown? Change every few months.
Apparently not totally separate e-mail addresses. Because that’s what they check, since you need an e-mail address to sign up, they check the addresses in the person’s PAB with their list and do the friend ask. Unless it was a cold e-mail, in which case they just send to all the addresses.