Normally, when a user registers, the registration will not be accepted when the user uses an email address that is not already in use. However, when the same email address is used as the one that the forum administrator uses this is not the case: the registration gets accepted. After that, even thought the account has not been approved yet, that user has access to the forum. This seems like a bug(?).
I tried for minutes to understand what you try to say, but failed.
Registration(s) is handled by Wordpress. Not by wpForo. And also what is "account approval" exactly. Doesn't seem like a WP standard feature. Do you use 3rd party plugins for registration and accounts ?
In our forum we require user approval when someone registers.
The situation is thus: when someone registers and this person use the same email address as the forum administrator, then this person gets access to the forum before the account is approved.
We do not use any 3th party plugins for registration and accounts.
I'm sorry but what you describe above JUST CAN'T HAPPEN.
If you try to register ANY email that already exist, WP returns:
ERROR: This email is already registered, please choose another one.
Also i don't understand how you manually approve users without a special plugin. There is no such option in WP.
Anonymous20 is right, there is no way to register two account with the same user. WP doesn't allow this, all issues you've described here are related to WordPress reg/login system, wpForo has no relation to these processes.