Any forum has IP checks, it a system check,
Im sure some people dont realize this, but this is not an unknown thing it happens on any forum regardless of the content of the forum itself.
When we see an IP its a long digit number that provides us with your mobile phone provider or internet provider you use, your basic general area like state, and city.
The city is almost always off , right now my IP says I live in Anchorage alaska, I live not even remotely close to anchorage.
When a user at rollitup creates a secondary account with the same IP it pops up , but just the number does, we the mod staff would have to physically check the number to see the information like service provider, state and city. And we at rollitup really dont care about that, what we care about is that someone is creating a second account under the same IP. To which than we check if its a spouse or friend creating an account or someone creating a "sock puppet" account to harass or troll the forum (which is than banned)
I cant speak for grasscity, but we at rollitup do not share this information with anyone, our mod staff are well respected people (civilians) who will not share your information.
And we on our servers side is well protected from any means of law enforcement, they cannot just come on here and get your IP.
Its really best if you fully understand what an IP address is , and how forums work before spreading mass paranoia rumors , those never help anyone. ever.