Bug: New Email List/Group using Thunderbird 140 Linux Mint

Bug?: In Address Book, I create a new Group list. In several of my Contacts, the individual has two different email addresses. I successfully add a person with their Primary email address. BUT, when I try to add a secondary email (i.e., add the same person a second time but using their non-primary email address), the Group List will re-list the primary address a second time and not accept a secondary email address. Is there a fix for this? {I'm using Linux Mint 22.3, Thunderbird 140.12.1esr 64, mint - 001-1.0}