Adding geometry (Ctrl+1) does not work as expected Sorry for the weird title, I didn't know how to express it better.

I have created a cube to form a hat.
I then extruded the 4 bottom vertices. 
I did not move them after extruding, but I simply scaled them.

Then I pressed Ctrl+1 to add geometry. 
For some reason, the hat brim is much smaller than I expected.

Shouldn't the hat brim be as large as the 4 extruded, scaled bottom vertices? 

And does anybody perhaps see why the hat brim gets doubled vertices?

Thank you for the help!
By pressing Ctrl 1 you added a Subsurf Modifier with one subdivision. The default subdivision agorithm is Catmull-Clark, which tends to round off the geometry, hence the roundness you see in the ghosted image. On the modifier you can change the subdivision from Catmull-Clark to Simple.