No, it should not be what you posted, it should be what I described. The help file explains very explicitly how -i behaves:
The -i switch indicates that the text should be inserted at the specified line instead of overwriting it. If you do not specify any text then a blank line is inserted. If you do not specify a line number then a blank line is added to the end of the file.
You need to do what RoCk suggested to get the results you want, but the -i behaviour is fine.
