Removing Double Faces Hi.  I'm new to Blender and started making modeling, till I ran into a problem.

I need help to remove a "Double Skin" as shown in the screenshot, as well as those blue lines.

The issue happened as I joined two objects and added mirror modifier.  I already tried removing doubles as well as removing modifiers, but to no avail.

Thank You!
When removing doubles you need to have everything selected. If that still doesn't work try selecting a section of one 'skin' and pressing Ctrl+L to select everything connected to it and then delete it.