1. Nope, not here specifically. In other places like Wikipedia and Wiki as a whole, other people use the same IP addresses. I would know this because some of my IP addresses are blocked from editing here and from others (banned in some places) due to abuse. I'm afraid my countrymen like to shitpost. As far as I can tell I'm the only one who visits and edits this Raildex wiki with those kinds of IP addresses. So if you see someone doing stuff here that are against the rules just block or ban them.
2. No. Though, I do visit the Contributions page of the IP and look if I've edited with it before.