Help! Duplicate Mesh popping up in Object Mode

Hi guys!

I’m new to Blender, and I just got Blender 2.57.1 on my PC and I’m having some issues with it in my modelling session. I made a simple head sculpt for my future models, and used these modifiers: Subdivision and Mirror. After doing my sculpt and applying the modifiers, in Object Mode I suddenly detect another duplicate mesh that’s inside the mesh I’ve done. Is this some sort of a bug or have I done something incorrect during the modelling process? Please help.

Some additional info: I have a duo core athlon running on Win XP

Here are some pictures.

Here is the Edit Mode screen.

http://i1102.photobucket.com/albums/g448/enzo20111/Blender%20Pics/EditMode.jpg

Now here is the Object Mode screen. Notice the mouth? That’s supposed to be hollow when its viewed in Edit Mode.

http://i1102.photobucket.com/albums/g448/enzo20111/Blender%20Pics/ObjectMode.jpg