But...after doing that, I look in the member list and the display nameI suspect this may be happening because your first add of them preset the Display Name stored in their account profile.
Then on the subsequent add the system saw that their account already had a Display Name, so defaulted their group profile to that rather than to what you put in the Direct Add.
Does the membership directory have a memory and is not flushing outI think it is neither the group's Directory nor its Members list (nor even Past Members, for premium groups).
Rather it is the account Groups.io created automatically for their email address when you did the first add of their address. You cannot delete or change their account information, so you won't be able to correct them except one by one through their group profile (which you can get to via their entry in the Members list).
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