Address Book does not allow duplicate email addresses

Screen shot please of what is blocking making/adding the duplicate, will get us more quickly to the cause.

Cannot provide a screenshot, in this instance, the address list is for a club, and we do get both husband & wife joining, and in some cases, they both use a common email address, but they need to be listed separately in the distribution list

Updating my Address Book in Thunderbird v148. The darned thing does not permit two people to have the same email address or phone number - pain in the "A" to say the least !

This is not my experience. See attached animation - these are local address books, not network ones. What could be the difference?

What is actually happening is that I go and "Edit List" for the "Mem Financial" list. I find the person's name which comes from the "Personal Address Book", and it appears to add that person into the list. However when I then reopen the "Mem Financial" list, that person is not in there, TBird just ignored the addition. This only happens when there is already another person in the list, different name but same email address.

This works for me (version 149) in mailing list - multiple contacts with same email address. And as far as I can tell there have been no code changes to mailing lists in at least a year.

Do Help > Troubleshoot Mode. Does it still fail?

Thanks Wayne, where did you get v149 from ? I've just checked their website and the only version available for download is v148, which is what I have been using.

Stay with 148. Wayne is using a pre-production release. Better to resolve with the production release.

Are you referring to an addressbook, or to a mailing list? I suggest first adding the second address to the addressbook.

It is actually a mailing list residing under the personal address book (see image). The people with the same email address are living quite happily in the "personal address book", but it just will not allow me to have the same situation in any of the 3 "Mem xxx" mailing lists under the address book.

Hey, super big thank you to Lin, that suggestion of yours did the trick, solved my problem ! Also thanks to everyone else who responded.