As far as I know you wouldn’t ever share an IP, only an IP range on a shared server.
2 sites would not both have the same IP’s. The first 2 series might be the same, and I guess in extreme cases 3, but not ever exactly the same.
This couldn’t happen;
your site 201.0.0.33
their site 201.0.0.33
It would be like this;
your site 201.0.45.133
their site 201.0.78.432