I'm so sorry you're dealing with some dummy addresses sneaking in. I reviewed your account and they appear to be coming in through a third party sign-up form you are using. I would check to see if the application gives you the ability to add a CAPTCHA security feature before they submit their info. This will prevent Internet bots from getting their dummy addresses through.
They will most definitely bounce, but we do not remove bounced addresses from your account so they will add to your Active Contacts total.
If you need additional support I encourage you to reach out to us at social_support(at)constantcontact(dot)com with your username and a reference to this post and we can assist you further.