Ahh, I think I figured it out. I am testing the invite system and so sending multiple invitations to the same email address (I only have so many). It looks like the invite link from the user profile “reuses” previous invitations. So, If I invited you to join a topic first, then I send an invitation from the user profile (to the forum)-- you get the topic invitation sent a 2nd time.
I just tried with a new email address and the user profile invitation is to the forum, not a topic.
Thanks for the quick responses.