There has been an odd bug lately where you can see two of people. It gets annoying when you think you are talking to a person, and they don't say or do anything. Sometimes i think my char need glasses .
Yes that has happened to me many times, it can be annoying but if you try and walk into the person you think may not be there, if it is indeed a 'ghost' then it will disappear when you walk through it.
No, it is caused by a client bug, where data is not correctly set after a person leaves a field. I have changed some of the code in the coming version, but I am not sure if its gone, because I was not able to reliantly reproduce the situation on the old version also.