Thanks guys for your suggestion, all effective althou a little "extra work" but it's my mistake, I didn't explain myself well. I just needed the surface to be copied within the same part not to export!. So someone suggested just to
Select the surface--Copy--Pasteand I get the surface as I wanted. Maybe it was too easy for you!
P.S.Got a lot of other "silly" problem....do you want to know?