Only you can see the small avatar image bottom right of the main avatar image, everyone else sees just the main one.
The small one is an indicator for you to see which threads you have posted in. The larger avatar image indicates the thread starter. In this case, as you are the thread starter, you see your avatar twice, the larger and the smaller. In threads started by others you'll see just their avatar where you haven't posted in the thread and in ones that you have, you'll see their avatar as the larger image and yours as the smaller bottom right.
It's a great indicator for users to quickly see which threads they have posted in.