I googled my name once (as you do) and, along with a load of references to the real me (so to speak) I found lots of references to other people with the same name -some even in similar lines of work or with similar interests.
We are none of use quite as unique as we might like to believe.
I presume they won't be with the same internet provider as you, otherwise, whoever was last to try and register their username would have been told that it's already been taken. And if they are using another internet provider, there's no problem, since your addresses will be different..