Alright, so I think I understand your problem? To get it straight, you were role-playing and you went on brb. When you came back, you SAW copy of yourself & roleplay partner, or HEARD it.
This is simple. I personally do not think that you were hacked. It is impossible for someone to be on the same account as you at the same time. If you were on your account and someone(the hacker) logged onto yours, you would be kicked off the server.
If you SAW the copy of yourself, did you look at the username? Rocker can be a pretty common name with wolves/huskies/dogs. If you simply heard yourself, this might be the same thing. If you double clicked on the 'copies' name in-game from the chat bar, it would have told you the username.
I also recommend that you talk it over with your RP partner again. Did he/she see the user? I have often seen people copy names and rp as those people. They might have just been trying to bug you. If you happened to get a look at their usernames, you might be able to contact them and/or see if they knew they had the same users. Sorry if I'm not too much help right now, it's very early where I am. Just calm down, because your account didn't get hacked. Hope I helped anyway~
Oh,so when someone gets into my account,I get kicked of the server? Oh wow,I'm very happy now because I wasn't kicked of the server when the "copy" was on there! Thank you so much,this really helped me! =D
But no,I didn't saw the "copies". I searched for them,but nothing. I think they just logged off or just left that place.
And I double clicked in my "copy" on the chat,but nothing appeared. Simply nothing.
But again,thank you. And sorry again if I was too nervous,but things like this really get me extremely nervous and worried. =/