Create A Forum - Support Forums

Hi,
Ok, so this is weird.

I had previously created a forum with Tapatalk groups that I had been experimenting with and that I ultimately decided not to use.
I then sent a friend the link for my forum created with Create a Forum. She registered. Create a forum sent me an email to approve the registration. I logged into the forum and approved her registration and sent the automatic generated email to notify her. So far, so good and as expected.
But then I received an email from Tapatalk confirming that she had joined the Tapatalk forum! I did not receive an email confirmation from Create a forum. She also says that she did not receive the confirmation email from  Create a Forum either.
I checked the members in Create a Forum and she is in fact registered and was able to log in. But she is also registered in Tap a Talk!
What is going on and what I can do to avoid it in the future?

Yes, nothing in spam.
The person I invited also received an email from tapatalk confirming her membership in the tapatalk forum... which she didn’t request!

I would need more information like what isp is the email. If you can pm me the emails that would help/date they signed up.

Tapatalk we have the mobile app on forums so you could find your forum though the app I belive but they shouldn't be auto registering members are their site I haven't seen that happen.