Activation Email

I have community blog build on wpmu/buddypress and thats working great. However, there is a specific problem when new user do the registration. As per the system flow, when user sign-up for blog, they get an activation email with an activation link. When user clicks on that link it takes him to screen where it says your account is activated please login this works fine.
The problem come in when user click on this activation link more than once, it takes them to screen which says please enter your activation key . Now we don't send any activation key to users so it puts them into loop.

Please advice as this is major problem on my blog