I wonder if Google has a backdoor API which lets group people by backup email. If one always creates an account with the previous email as a backup, the link is

I wonder if Google has a backdoor API which lets group people by backup email. If one always creates an account with the previous email as a backup, the link is east to make. That would be especially useful for censorship services across competitors: Although Google Facebook and Twitter compete, sharing the flagged accounts would allow recognizing the same user coming back with a different email address.