This has happened a few times to me.
Once was on Maxwell, now he is a fairly easy char to copy but I love him, and there was a person named Snow who had the exact same colors, same markings, a different style mane and name were the only different things from what I can remember. Now in Maxy's bio I have it that he walks everywhere, and this person was doing just that. They followed me when I moved to another spot and they stared at me sometimes, I think they even mentioned that we look similar but I have a feeling he was a copier...
And it really kills me when someone copies Thyme without my permission. Mainly the ones who do the exacts eyes, because her eyes I don't see a lot of people use. I had a friend who, once she met me, she started to make her chars look very much alike to Thyme. Once a friend of mine tried to copy her as well, almost exact, she thought it was funny but I didn't, neither did my other friends. I only allow for copiers when I am either making a mini army of similar Thyme's or just for the fun of it.
But yeah, it bugs me a lot, not so much anymore because I just ignore them now and it seems like less and less people are doing it to me, which is nice. But yeah, glad you know to block instead of get all worked up and give them the pleasure of laughing in your face.