20 Diff Ip's For One Person

Hey guys. . .

I'm not really sure what the deal is with the Ip's, but the other Admin & I just wrote down the Ip's for our forum users.

What I'm having issues with, is It says "ip used by this user" or what not, then says "other ip's used by this person"
Under my name there is like 20 different Ip's??

I don't understand why! I use this one comp & the same internet server. .

Being that I myself have that many apparently, what happens when we have someone pretending to be someone else?
Would we ever know? Or not really

IP is Connection's Location!
I think 20 diff IP is because User use diff 20 computer at the time!

Or the user has a dynamic IP one that changes every time he turns on his computer.
Now normal for many isp's.