How many users are showing the thread?

Ok so I was looking in a thread, and I saw that 2 members where viewing the thread, but only 1 name showed, my own..

I was wondering how this is possible. Is there a way to hide your name or something? I refreshed and it stayed the same, so can't have to do something with that. Any ideas?

It's most likely due to the person selecting "Invisibility Mode" in the User CP options. This will hide your name on Active-viewing/online list's from normal user's - ie select it, and your name won't appear on the "viewing forum/thread" section to others (you will always see your own name).