Why those few edges look differently?

I am trying to understand why those few edges look differently? Are those double edges? I tried to select ALL and to remove the doubles but nothing changed. If they are double edges how can I remove them if the remove doubles doesn’t work? Or Is it some topology trick?

those edges are marked sharp

select them, press ctrl+e and click ‘clear sharp’

Thanks. I did it. Some of the edges needed 2 or more tries to clear the sharpness; and the last edge remained uncleared until I A-selected all the mesh and then the Clear Sharp worked on it too. No idea why.