I had 3 extra (2 visible behind my front teeth, kind of in the roof of my mouth...the other one was not through the gum, was seen on xray, and was fully upside down. They made that one a case for research).
They removed mine surgically, since they were taking out the upside down one anyway and teeth on the roof of the mouth impede the tongue for speech.
My ds also had 2. We noticed when a front tooth fell out and 2 new front teeth tried to squeeze in there. Caught it really quickly, actually. They said there was another front tooth under those 2, so pulled them both surgically (under anesthesia). Lo and behold, a front tooth grew in!
My youngest dd had a tooth that was nearly 2 teeth. It was 2 teeth fused. Since it was a baby tooth, they just let her keep her extra-wide tooth. It fell out last year.
As you can see, this runs in my family, lol. Although 2 members of my family were missing 2 teeth (the ones on either side of the top 2 front teeth). They just live with it, and nobody ever even notices.