IP madness

IP address madness!  I was reading a slave's profile, wherein he told how to look up someone's IP address. Going to the site, I was immediately told what my IP address is, and, that it is listed with three databases as being a spammer. So, I went and looked up those three databases. Two of them did not have that IP address listed, and one didn't even exist. Then, I see something that says I can look up geographical information and put the IP address in there. It gave me results from two different providers. One said I was in Tucson, AZ. The other one said I was in Denver, Colorado. Weird, eh?Well, maybe the person in Denver is a spammer? I thought IP addresses are supposed to be unique, though?